fix: make the update checker visible -- persistent banner + a menu item

Reported from the field: running v1.2 against a repo with v1.3.0 published
gave no prompt, and there appeared to be no way to check manually. The
checker itself works; it was invisible, for two reasons.

#78 -- the notice was written to the shared status label, which 21 other
call sites rewrite. The check runs off-thread and lands a second or two
after launch, right as the user starts clicking, so the next selection or
refresh wiped it. Exactly the bug fixed for the MSIX warning in #35, which
got a persistent banner; that fix was never carried to the update notice.

Adds NoticeBanner: a persistent, dismissible notice carrying its own action
button. It's a shared widget rather than a second bespoke banner, so the
next thing needing the user's attention doesn't reach for the status bar
again. (The MSIX banner still uses its own QLabel -- migrating it is a
follow-up, deliberately not bundled with a bug fix.)

#79 -- the only 'Check for updates' affordance was a button inside the
About dialog, which is not where anyone looks. Worse, the About action was
created without a menu role, and Qt auto-assigns AboutRole to actions whose
text begins with 'About', relocating it into the macOS application menu --
so the notice's own hint, 'Help > About to view it', pointed at a menu that
on macOS doesn't contain the item.

Help now has its own 'Check for updates...' item with an explicit
ApplicationSpecificRole, and the About action states its AboutRole rather
than inheriting it invisibly. The menu-driven check is never throttled and
always reports back -- the user asked, so silence would read as broken.

The decision and the wording live in core.update_notice() because the test
suite has no PySide6 (CI installs pytest + cryptography only), so anything
in bcc.py is untestable. A test asserts the notice text names no menu path,
which is what went stale here in the first place.

Closes #78
Closes #79

bcc.py

@@ -10,6 +10,7 @@ Run:  python mcp_manager.py
 
 from __future__ import annotations
 
+import contextlib
 import sys
 import time
 from pathlib import Path
@@ -130,6 +131,10 @@ QScrollBar::handle:vertical {{ background: {BORDER}; border-radius: 5px; min-hei
 QScrollBar::add-line, QScrollBar::sub-line {{ height: 0; }}
 QLabel#statusbar {{ color: {MUTED}; padding: 4px 2px; }}
 QLabel#warnBanner {{ color: #1a1205; background: {WARN}; border-radius: 8px; padding: 8px 10px; font-weight: 600; }}
+QFrame#noticeBanner {{ background: {PANEL_2}; border: 1px solid {ACCENT}; border-radius: 8px; }}
+QLabel#noticeText {{ color: {TEXT}; }}
+QPushButton#noticeClose {{ background: transparent; border: none; color: {MUTED}; font-size: 14px; padding: 2px; }}
+QPushButton#noticeClose:hover {{ color: {TEXT}; }}
 QLabel#section {{ color: {MUTED}; font-weight: 600; font-size: 12px; padding: 2px 2px; }}
 QLabel#sectionDisabled {{ color: {MUTED}; font-weight: 600; font-size: 12px; padding: 2px 2px; }}
 QLabel#placeholder {{ color: {MUTED}; padding: 12px; background: {PANEL_2}; border: 1px dashed {BORDER}; border-radius: 8px; }}
@@ -1493,6 +1498,54 @@ class AboutDialog(QDialog):
         QDesktopServices.openUrl(QUrl(self._release_url or core.RELEASES_URL))
 
 
+class NoticeBanner(QFrame):
+    """A persistent, dismissible notice with an optional action button.
+
+    The status bar is the wrong home for anything the user needs to act on --
+    21 call sites rewrite it, so a message posted there is gone by the next
+    click. That wiped the MSIX warning (#35) and then the update notice (#78).
+    This is the shared mechanism so it doesn't happen a third time.
+    """
+
+    def __init__(self, parent=None):
+        super().__init__(parent)
+        self.setObjectName("noticeBanner")
+        row = QHBoxLayout(self)
+        row.setContentsMargins(10, 8, 8, 8)
+        row.setSpacing(8)
+        self._label = QLabel("")
+        self._label.setObjectName("noticeText")
+        self._label.setWordWrap(True)
+        row.addWidget(self._label, 1)
+        self._action_btn = QPushButton("")
+        self._action_btn.setCursor(Qt.CursorShape.PointingHandCursor)
+        self._action_btn.hide()
+        row.addWidget(self._action_btn)
+        self._close_btn = QPushButton("\u2715")
+        self._close_btn.setObjectName("noticeClose")
+        self._close_btn.setCursor(Qt.CursorShape.PointingHandCursor)
+        self._close_btn.setFixedWidth(26)
+        self._close_btn.setToolTip("Dismiss")
+        self._close_btn.clicked.connect(self.hide)
+        row.addWidget(self._close_btn)
+        self.hide()
+
+    def show_notice(self, text: str, action_label: str = "", on_action=None):
+        self._label.setText(text)
+        self._label.setToolTip(text)
+        # Reconnect cleanly: a banner reused for a second notice would
+        # otherwise fire the previous notice's action too.
+        with contextlib.suppress(RuntimeError, TypeError):
+            self._action_btn.clicked.disconnect()
+        if action_label and on_action is not None:
+            self._action_btn.setText(action_label)
+            self._action_btn.clicked.connect(lambda _=False: on_action())
+            self._action_btn.show()
+        else:
+            self._action_btn.hide()
+        self.show()
+
+
 # --------------------------------------------------------------------------- #
 # Restart worker: core.restart_claude_desktop() blocks up to ~5 s on macOS
 # waiting for the old instance to exit, so it must run off the UI thread.
@@ -1550,6 +1603,11 @@ class MainWindow(QMainWindow):
         self.warn_banner.hide()
         root.addWidget(self.warn_banner)
 
+        # Update availability gets its own persistent banner rather than a
+        # status-line write, which the next UI action overwrites (#78).
+        self.update_banner = NoticeBanner(self)
+        root.addWidget(self.update_banner)
+
         # User-draggable divider between the server list and the editor.
         split = QSplitter(Qt.Orientation.Horizontal)
         split.setChildrenCollapsible(False)
@@ -1586,10 +1644,59 @@ class MainWindow(QMainWindow):
     # --- menu bar ---------------------------------------------------------- #
     def _build_menu_bar(self):
         help_menu = self.menuBar().addMenu("&Help")
+
+        # "Check for updates" used to exist only as a button inside the About
+        # dialog, which is not somewhere anyone looks for it (#79).
+        update_action = QAction("Check for updates…", self)
+        # Explicit role: macOS relocates actions it recognises by text, and
+        # some Qt versions treat "update" as application-menu material. Pin it
+        # so the item stays where the menu says it is on every platform.
+        update_action.setMenuRole(QAction.MenuRole.ApplicationSpecificRole)
+        update_action.triggered.connect(self.check_for_updates)
+        help_menu.addAction(update_action)
+        help_menu.addSeparator()
+
         about_action = QAction("About Better Claude Config…", self)
+        # Qt auto-assigns AboutRole to actions whose text starts with "About",
+        # which moves this into the application menu on macOS. That is the
+        # right home there -- state it explicitly rather than inheriting it by
+        # accident, since the behaviour is invisible from this call site.
+        about_action.setMenuRole(QAction.MenuRole.AboutRole)
         about_action.triggered.connect(self._show_about)
         help_menu.addAction(about_action)
 
+    def _show_update_notice(self, notice: dict):
+        """Surface an available update where it survives the next click."""
+        url = notice["url"]
+        self.update_banner.show_notice(
+            notice["text"],
+            action_label="Open releases page",
+            on_action=lambda: QDesktopServices.openUrl(QUrl(url)),
+        )
+
+    def check_for_updates(self):
+        """Menu-driven check. Unlike the startup check this is never throttled
+        and always reports back -- the user asked, so silence would read as a
+        broken button."""
+        self.status.setText("Checking for updates…")
+        self._menu_update_worker = UpdateCheckWorker()
+        self._menu_update_worker.done.connect(self._on_menu_update_checked)
+        self._menu_update_worker.start()
+
+    def _on_menu_update_checked(self, release: dict | None):
+        self._menu_update_worker = None
+        if release is None:
+            self.status.setText("Couldn't check for updates (offline?).")
+            return
+        QSettings("BCC", "BetterClaudeConfig").setValue("update/lastCheck", time.time())
+        notice = core.update_notice(core.__version__, release)
+        if notice:
+            self._show_update_notice(notice)
+            self.status.setText(f"Update available: {notice['version']}")
+        else:
+            self.update_banner.hide()
+            self.status.setText(f"You're up to date ({core.__version__}).")
+
     def _show_about(self):
         AboutDialog(self).exec()
 
@@ -1610,10 +1717,9 @@ class MainWindow(QMainWindow):
         if release is None:
             return  # offline/failed check: don't advance lastCheck, allow retry
         QSettings("BCC", "BetterClaudeConfig").setValue("update/lastCheck", time.time())
-        if core.is_newer_version(core.__version__, release["version"]):
-            self.status.setText(
-                f"Update available: {release['version']}  ·  Help ▸ About to view it."
-            )
+        notice = core.update_notice(core.__version__, release)
+        if notice:
+            self._show_update_notice(notice)
 
     # --- layout persistence ---------------------------------------------- #
     def _restore_layout(self):