[P3] Permission request timeout (auto-deny after 30s)

[quangdang46]

Permission Request Timeout

Priority: P3 · Effort: 0.5 day

Current

Pending permission dialog stays open indefinitely.

Target

Auto-deny after timeout (30 seconds for automatic/headless agents).

Implementation

1. Add pending_permission_at: Option<Instant> to App (app.rs)
2. Check expiry before rendering dialog (ui.rs or local.rs)
3. Auto-deny + notify if timed out

Acceptance Criteria

• Permission request auto-denies after 30 seconds
• User is notified when auto-deny fires
• Configurable timeout (default 30s)