feat(catalog-console): a keys status command, and complete rotation without a red main (#62, #68)

Two problems from issue #68's follow-up review:

1. The maintainer -- the only person who will ever use this tool -- cannot
   reliably tell which of the two signing keys is which or what state
   either is in. He already pasted a private key into a chat window
   because a prompt was ambiguous. That's a defect in this tool, not user
   error.

2. PR #71 rotates bcc_core.CATALOG_PUBKEYS, which makes
   data/catalog.json.sig (signed by the retired key) stop verifying and
   the CI catalog-signature job go red. The Console could previously only
   load/sign against `main`, so the only way through was to merge a red
   PR and fix main afterwards -- normalizing exactly the alarm fatigue
   this whole design exists to prevent.

Task 1 -- `python catalog_console.py keys`:
  A plain-English-first status report for BOTH keys: purpose, where the
  private half lives, whether it exists locally, its fingerprint, whether
  that fingerprint matches every place its public half is expected to be
  committed (bcc_core.CATALOG_PUBKEYS, ci.yml's trust anchor, and
  scripts/sign_checksums.RELEASE_PUBKEYS -- checked independently, since
  issue #68 finding 4 was exactly bcc_core.py and ci.yml silently
  drifting apart), and whether data/catalog.json.sig currently verifies --
  ending with the exact command to run next. Needs no passphrase and never
  touches private key bytes: a plaintext public-key cache
  (store_public_key/load_public_key) is written alongside the existing
  encrypted private blob at keygen time, precisely so this command can
  report a fingerprint without decrypting anything.

  The status/report logic (key_status, render_key_status_report,
  recommend_next_steps, fingerprint_pubkey, extract_pubkey_list_literal,
  extract_ci_trust_anchor_pubkey) is pure and lives in catalog_review.py;
  cmd_keys in catalog_console.py is a thin printer over it, per the
  project's existing pure-core/thin-GUI split.

Task 2 -- rotation completable without a red main:
  ReviewWindow now offers a "current branch" source (auto-detected via
  `current_branch()`, or --ref to name one explicitly) alongside "main"
  and open PRs. Loading it runs the exact same diff-against-last-signed /
  rotation-detection logic "main" always used (_load_own_ref, extracted
  from the old hardcoded-to-main _on_load), just parameterized on the
  ref. Signing now pushes to session.loaded_ref, never a hardcoded "main"
  (commit_and_push_signed_catalog's branch param was already there --
  only the call site was wrong). The ref-list computation itself is a
  pure function (compute_own_refs) so this seam is unit-testable without
  git or Qt. None of can_sign()'s guards (empty-diff, acknowledge-all,
  blocking-risk, TOCTOU) were touched.

  This lets a rotation branch be reviewed, re-attested (every entry,
  since the new key never vouched for any of them -- issue #68 finding 5
  follow-up), signed, and pushed to ITS OWN branch before it's ever
  merged.

Task 3 -- label the keys everywhere:
  PassphraseDialog now shows which key (CATALOG vs RELEASE) and its
  fingerprint before the passphrase field, both in its window title and
  its prompt text -- the exact ambiguity that led to a private key being
  pasted into a chat window. cmd_keygen's stored-key confirmation now
  reads "CATALOG private key encrypted..." / "RELEASE private key
  encrypted..." instead of a capitalized-lowercase kind. The reattest
  banner now says "CATALOG signing key" / "CATALOG key" throughout
  instead of "the key".

PySide6's import is now guarded (try/except -> _PYSIDE6_AVAILABLE) and
every GUI class definition that depends on it moved under
`if _PYSIDE6_AVAILABLE:`. `keygen`, `show-seed-b64`, and the new `keys`
command have no GUI dependency and now work (and are testable) in an
environment without PySide6 -- which is exactly this repo's own `test`
CI job (pytest + cryptography only, no PySide6). `gui` fails with a clear
message instead of an ImportError stack trace if it's missing.

Tests: 26 new pure-function tests in tests/test_catalog_review.py
(fingerprint_pubkey, extract_pubkey_list_literal,
extract_ci_trust_anchor_pubkey, key_status, recommend_next_steps,
render_key_status_report) and a new tests/test_catalog_console_git.py
(14 tests) covering compute_own_refs, current_branch,
commit_and_push_signed_catalog's branch targeting, and
catalog_sig_status_on_disk against real local git repos -- importing
catalog_console.py directly, proving it works without PySide6. 400
passed, 1 skipped (pre-existing). ruff check / ruff format --check clean.

tests/test_catalog_review.py

@@ -785,3 +785,245 @@ def test_contains_non_ascii_true():
 
 def test_contains_non_ascii_false():
     assert r.contains_non_ascii("package") is False
+
+
+# --------------------------------------------------------------------------- #
+# fingerprint_pubkey
+# --------------------------------------------------------------------------- #
+def test_fingerprint_pubkey_is_deterministic():
+    pub = b"\x01" * 32
+    assert r.fingerprint_pubkey(pub) == r.fingerprint_pubkey(pub)
+
+
+def test_fingerprint_pubkey_differs_for_different_keys():
+    assert r.fingerprint_pubkey(b"\x01" * 32) != r.fingerprint_pubkey(b"\x02" * 32)
+
+
+def test_fingerprint_pubkey_never_contains_the_key_bytes_themselves():
+    pub = b"\x42" * 32
+    fp = r.fingerprint_pubkey(pub)
+    assert pub.hex() not in fp.lower().replace(" ", "")
+
+
+# --------------------------------------------------------------------------- #
+# extract_pubkey_list_literal / extract_ci_trust_anchor_pubkey: text parsing
+# for `catalog_console.py keys`, exercised here with no file I/O.
+# --------------------------------------------------------------------------- #
+def test_extract_pubkey_list_literal_single_key():
+    _seed, pub = r.generate_keypair()
+    import base64
+
+    text = (
+        "CATALOG_PUBKEYS: list[bytes] = [\n"
+        f'    base64.b64decode("{base64.b64encode(pub).decode()}"),\n'
+        "]\n"
+    )
+    assert r.extract_pubkey_list_literal(text, "CATALOG_PUBKEYS") == [pub]
+
+
+def test_extract_pubkey_list_literal_multiple_keys():
+    import base64
+
+    pubs = [r.generate_keypair()[1] for _ in range(2)]
+    body = ",\n".join(f'    base64.b64decode("{base64.b64encode(p).decode()}")' for p in pubs)
+    text = f"RELEASE_PUBKEYS: list[bytes] = [\n{body},\n]\n"
+    assert r.extract_pubkey_list_literal(text, "RELEASE_PUBKEYS") == pubs
+
+
+def test_extract_pubkey_list_literal_missing_variable_returns_empty():
+    assert r.extract_pubkey_list_literal("some unrelated text", "CATALOG_PUBKEYS") == []
+
+
+def test_extract_pubkey_list_literal_does_not_match_a_different_variable():
+    import base64
+
+    _seed, pub = r.generate_keypair()
+    text = f'OTHER_PUBKEYS: list[bytes] = [base64.b64decode("{base64.b64encode(pub).decode()}")]\n'
+    assert r.extract_pubkey_list_literal(text, "CATALOG_PUBKEYS") == []
+
+
+def test_extract_ci_trust_anchor_pubkey_found():
+    import base64
+
+    _seed, pub = r.generate_keypair()
+    text = f'          EXPECTED_CATALOG_PUBKEY_B64: "{base64.b64encode(pub).decode()}"\n'
+    assert r.extract_ci_trust_anchor_pubkey(text) == pub
+
+
+def test_extract_ci_trust_anchor_pubkey_missing_returns_none():
+    assert r.extract_ci_trust_anchor_pubkey("no anchor here") is None
+
+
+# --------------------------------------------------------------------------- #
+# key_status / render_key_status_report / recommend_next_steps
+# --------------------------------------------------------------------------- #
+def _kw(**overrides):
+    base = dict(
+        kind="catalog",
+        display_name="CATALOG",
+        purpose="Signs the catalog.",
+        private_key_location="on this machine",
+        local_exists=True,
+        local_pubkey=b"\x01" * 32,
+        locations=[("bcc_core.CATALOG_PUBKEYS", [b"\x01" * 32])],
+        catalog_sig_status="valid",
+    )
+    base.update(overrides)
+    return base
+
+
+def test_key_status_reports_match_when_local_pubkey_in_committed_list():
+    status = r.key_status(**_kw())
+    assert status.locations[0].status == "match"
+
+
+def test_key_status_reports_mismatch_when_local_pubkey_not_in_committed_list():
+    status = r.key_status(**_kw(locations=[("bcc_core.CATALOG_PUBKEYS", [b"\x02" * 32])]))
+    assert status.locations[0].status == "mismatch"
+
+
+def test_key_status_reports_unknown_when_no_local_pubkey():
+    status = r.key_status(**_kw(local_pubkey=None, local_exists=False))
+    assert status.locations[0].status == "unknown"
+    assert status.local_fingerprint is None
+
+
+def test_key_status_never_carries_a_local_fingerprint_when_key_absent():
+    status = r.key_status(**_kw(local_pubkey=None, local_exists=False))
+    assert status.local_exists is False
+    assert status.local_fingerprint is None
+
+
+def test_key_status_fingerprint_matches_fingerprint_pubkey_helper():
+    pub = b"\x03" * 32
+    status = r.key_status(**_kw(local_pubkey=pub, locations=[("x", [pub])]))
+    assert status.local_fingerprint == r.fingerprint_pubkey(pub)
+
+
+def test_key_status_checks_multiple_locations_independently():
+    """A key can match one committed location and mismatch another -- this
+    is exactly the drift issue #68 finding 4 was about (bcc_core.py and
+    ci.yml silently disagreeing on the trust anchor)."""
+    pub = b"\x04" * 32
+    other = b"\x05" * 32
+    status = r.key_status(
+        **_kw(
+            local_pubkey=pub,
+            locations=[
+                ("bcc_core.CATALOG_PUBKEYS", [pub]),
+                ("ci.yml trust anchor", [other]),
+            ],
+        )
+    )
+    assert status.locations[0].status == "match"
+    assert status.locations[1].status == "mismatch"
+
+
+def test_recommend_next_steps_flags_never_generated_key():
+    status = r.key_status(**_kw(local_exists=False, local_pubkey=None, locations=[]))
+    steps = r.recommend_next_steps([status])
+    assert any("keygen" in s and "CATALOG" in s for s in steps)
+
+
+def test_recommend_next_steps_release_key_uses_release_flag():
+    status = r.key_status(
+        kind="release",
+        display_name="RELEASE",
+        purpose="Signs checksums.",
+        private_key_location="not generated yet",
+        local_exists=False,
+        local_pubkey=None,
+        locations=[],
+    )
+    steps = r.recommend_next_steps([status])
+    assert any("keygen --release" in s for s in steps)
+
+
+def test_recommend_next_steps_flags_mismatch_by_location_name():
+    status = r.key_status(**_kw(locations=[("bcc_core.CATALOG_PUBKEYS", [b"\x99" * 32])]))
+    steps = r.recommend_next_steps([status])
+    assert any("bcc_core.CATALOG_PUBKEYS" in s and "CATALOG" in s for s in steps)
+
+
+def test_recommend_next_steps_flags_invalid_catalog_signature():
+    status = r.key_status(**_kw(catalog_sig_status="invalid"))
+    steps = r.recommend_next_steps([status])
+    assert any("re-signing" in s for s in steps)
+
+
+def test_recommend_next_steps_flags_missing_catalog_signature():
+    status = r.key_status(**_kw(catalog_sig_status="missing"))
+    steps = r.recommend_next_steps([status])
+    assert any("re-signing" in s for s in steps)
+
+
+def test_recommend_next_steps_all_clear_when_nothing_wrong():
+    status = r.key_status(**_kw())
+    steps = r.recommend_next_steps([status])
+    assert steps == ["Everything is consistent -- no action needed."]
+
+
+def test_recommend_next_steps_release_key_has_no_catalog_signature_advice():
+    """A mismatched RELEASE key must never trigger catalog-signing advice --
+    the two keys' remediation paths must not bleed into each other."""
+    status = r.key_status(
+        kind="release",
+        display_name="RELEASE",
+        purpose="Signs checksums.",
+        private_key_location="on this machine",
+        local_exists=True,
+        local_pubkey=b"\x06" * 32,
+        locations=[("scripts/sign_checksums.py RELEASE_PUBKEYS", [b"\x07" * 32])],
+        catalog_sig_status=None,
+    )
+    steps = r.recommend_next_steps([status])
+    assert not any("re-signing" in s for s in steps)
+    assert any("RELEASE" in s for s in steps)
+
+
+def test_render_key_status_report_never_prints_private_key_material():
+    """The report string must be built ONLY from public inputs. Sanity
+    check: no field on KeyStatus/PubkeyLocationCheck is capable of holding
+    private key bytes in the first place (there's no such field to leak),
+    and the render function only touches fields that exist -- this test
+    guards against a future field addition reintroducing that risk."""
+    status = r.key_status(**_kw())
+    text = r.render_key_status_report([status])
+    assert "CATALOG" in text
+    assert (
+        "purpose" not in text.lower() or "Signs the catalog." in text
+    )  # sanity, not a real secret
+    # No 64-hex-char (or longer) run anywhere -- a raw 32-byte seed/sig
+    # would show up as one if it were ever accidentally interpolated in.
+    import re as _re
+
+    assert not _re.search(r"[0-9a-fA-F]{64,}", text)
+
+
+def test_render_key_status_report_names_the_specific_key_not_generic_the_key():
+    status = r.key_status(**_kw())
+    text = r.render_key_status_report([status])
+    assert "CATALOG KEY" in text
+    assert "the key" not in text.lower()
+
+
+def test_render_key_status_report_includes_catalog_signature_line_only_for_catalog():
+    catalog_status = r.key_status(**_kw())
+    release_status = r.key_status(
+        kind="release",
+        display_name="RELEASE",
+        purpose="Signs checksums.",
+        private_key_location="on this machine",
+        local_exists=True,
+        local_pubkey=b"\x08" * 32,
+        locations=[("scripts/sign_checksums.py RELEASE_PUBKEYS", [b"\x08" * 32])],
+        catalog_sig_status=None,
+    )
+    text = r.render_key_status_report([catalog_status, release_status])
+    assert text.count("Catalog signature:") == 1
+
+
+def test_render_key_status_report_ends_with_what_to_do_next_section():
+    status = r.key_status(**_kw())
+    text = r.render_key_status_report([status])
+    assert "What to do next:" in text