🧪 Add tests for useReconcileSweep hook

[Matuyuhi]

🎯 What: Added missing test coverage for the useReconcileSweep hook.
📊 Coverage: The new tests cover:

• Hook mounting behavior (sends reconcile message and triggers refreshPrefs).
• Dropped tab handling (triggers refresh if dropped > 0, skips if dropped === 0).
• Visibility change handling (re-triggers sweep when visibility state becomes visible).
• Cleanup (event listeners are properly removed on unmount).
  ✨ Result: Increased test coverage to capture edge cases and lifecycle events for the useReconcileSweep hook. Installed @testing-library/react, @testing-library/user-event, and jsdom to support these tests.

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PR created automatically by Jules for task 5816285228147880637 started by @Matuyuhi

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