fix: confirm before quitting when unsaved review work would be lost

[mvanhorn]

Summary

Pressing q/Esc to quit now asks for confirmation when you have unsaved review work (draft notes, user notes, or live comments), so you no longer lose in-progress review input by accidentally quitting. Quitting with nothing unsaved still exits immediately.

Why this matters

Issue #499 reports losing review work by quitting without warning. This adds a quit-confirmation dialog gated on whether there is actually unsaved, in-memory review work to lose. Crucially, it ignores persisted/static agent sidecar annotations (file.agent.annotations): those reload on the next launch and are not lost on quit, so an agent-context review no longer shows a spurious "notes will be lost" prompt when the user has not authored anything.

Changes

• QuitConfirmDialog component + useAppKeyboardShortcuts wiring for q/Esc.
• The quit gate counts only draft notes, user notes, and live comments — not static agent annotations — so it prompts exactly when unsaved work exists.

Testing

bun test AppHost.interactions.test.tsx passes (65 tests) and bun run typecheck is clean. New coverage asserts: quitting with only agent sidecar annotations does not prompt, while a draft/user note/live comment does prompt, and confirming/cancelling behaves correctly.

Fixes #499

[greptile-apps]

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