Task 1c — Show low-confidence visual indicator on desktop widget

Task 1c — Visual indicator for low-confidence rejection

Part of Task 1: Low Confidence Voice Feedback. Depends on #373 (Task 1a).

What to do

Using the low-confidence event from Task 1a, update the desktop widget UI to show a visual indicator when confidence is too low.

• Find where the desktop widget receives listener state updates.
• Add a new transient state (e.g. LOW_CONFIDENCE) that displays a visual cue — for example a subtitle line like "Didn't catch that...", a colour change on the listening indicator, or a brief shake/pulse animation.
• The indicator should auto-dismiss after ~2 seconds and return to normal idle/listening state.
• Do not change any TTS logic — this is UI only.

Files to touch

• Desktop widget / tray UI layer (wherever listener state is rendered)
• src/jarvis/listening/state_manager.py (if a new state constant is needed)

Acceptance criteria

• Widget shows a visible low-confidence cue when transcript is rejected
• Cue disappears automatically after ~2 seconds
• No visual change for normal successful transcripts
• Works on all supported platforms (Windows, macOS, Linux)