Adds a subtle ArchivedNoteBanner component below the breadcrumb bar
when a note is archived. Banner includes:
- Muted gray background with archive icon + 'Archived' label
- 'Unarchive' button (ArrowUUpLeft icon) wired to same handler as Cmd+E
- Keyboard hint shown in button title
Editor remains fully editable (banner is purely informational).
Indicator appears/disappears reactively via entry.archived from store.
Co-authored-by: Test <test@test.com>
