Fix browser fallback startup activity when desktop bridge is missing

[Hector-Ha]

Parent

#28

What to build

Make InstantRepo startup status truthful when the frontend is running in a browser without the Wails desktop bridge. The first Recent Events item should match the unavailable desktop-controls banner instead of saying desktop controls are live.

Acceptance criteria

• Browser fallback startup shows a warning/critical activity that desktop controls are unavailable.
• Desktop bridge-present startup still shows the normal ready activity.
• Desktop API calls remain fail-closed when the bridge is missing.
• Frontend tests cover bridge-present and bridge-missing startup activity behavior.
• The issue remains open after the fix is implemented.

Blocked by

#28