PyCForge 1.3.27 — Immediate stale scan feedback

Behavior
- Editing a scanned source immediately disables old findings in the full Python check dialog and compact recent-scan dropdown.
- Disabled panels are muted and identify old locations as SCANNED LINE.
- Clean results also become stale rather than continuing to present a clean result for changed code.
- Hidden scan dialogs track edits. Split-editor edits, source rename/close and changes to included companions invalidate the same scan.
- Unscanned module edits and tab switching alone do not invalidate the scan.
- Undo does not revive invalidated findings. A new completed scan of unchanged source restores navigation with refreshed locations.
- Results finishing after a source edit remain stale.
- Old issue objects and queued navigation callbacks from previous scans are rejected.
- The recent-scan arrow remains available to inspect stale feedback and open the full scan dialog. Re-scan remains available.

Verification
- 25 existing Tools/Python-check UI tests passed.
- 13 new freshness tests passed at normal scale.
- 14 freshness tests passed at 150% scaling, including an additional queued-navigation/new-scan race case.
- Tested immediate disabling before source debounce, undo, hidden edits, edits during scanning, companion opt-in, unrelated files, split editing, rename/close, clean-result invalidation, refreshed line numbers and Windows CRLF normalization.
- Stale full-dialog and dropdown rendering visually inspected.
- Only scan UI, version and help package files changed. The Python analysis engine, converter and conversion-diagnostics shortcut are unchanged.
- Tests ran on Linux Qt offscreen. Native Windows behavior remains for user verification.

Windows check
1. Scan Python containing an issue, then open the compact results dropdown.
2. Insert or remove a line in the scanned editor. Both result views should immediately mark the old findings stale and disable clicking/keyboard navigation.
3. Undo that edit. Old findings should stay stale.
4. Re-scan. New findings should use current locations and navigate correctly.
5. Repeat with the scan dialog closed and with an included companion module edited.
6. Check a previously clean scan: editing must replace the clean status with stale feedback.

No new application dependencies. Install the single 1.3.27 wheel into the existing environment.
