feat: clearer Arguments editor with typed-together detection and one-click fix

- Label now explains the model with an example: a flag and its value go
  on separate lines. Placeholder shows the common uv pattern.
- split_suspicious_args() flags lines that contain whitespace plus a
  dash-prefixed token ('--directory /path') — legit single args with
  spaces ('My Documents') are never touched. Quotes are respected.
- The editor shows a warning under the args box with a 'Fix: split onto
  separate lines' button; the fix goes through the undo stack.

tests/test_json_repair.py

@@ -172,6 +172,40 @@ def test_kitchen_sink():
     assert len(notes) >= 4
 
 
+# --------------------------------------------------------------------------- #
+# Suspicious-args detection (several argv tokens typed on one line)
+# --------------------------------------------------------------------------- #
+def test_split_flag_and_value_on_one_line():
+    fixed, notes = c.split_suspicious_args(["--directory /path/to/server", "run", "main.py"])
+    assert fixed == ["--directory", "/path/to/server", "run", "main.py"]
+    assert len(notes) == 1
+
+
+def test_split_full_option_string():
+    fixed, notes = c.split_suspicious_args(["-y @pkg/server --port 8080"])
+    assert fixed == ["-y", "@pkg/server", "--port", "8080"]
+    assert notes
+
+
+def test_split_respects_quotes():
+    fixed, _ = c.split_suspicious_args(['--name "My Server"'])
+    assert fixed == ["--name", "My Server"]
+
+
+def test_split_leaves_legit_spaces_alone():
+    args = ["/Users/me/My Documents", "hello world", "run"]
+    fixed, notes = c.split_suspicious_args(args)
+    assert fixed == args
+    assert notes == []
+
+
+def test_split_leaves_clean_args_alone():
+    args = ["--directory", "/path/to/server", "run", "main.py"]
+    fixed, notes = c.split_suspicious_args(args)
+    assert fixed == args
+    assert notes == []
+
+
 # --------------------------------------------------------------------------- #
 # Config-file repair (load-time)
 # --------------------------------------------------------------------------- #