fix: add missing cleanup for event listeners and debounce timer

[collinsezedike]

Summary

• usePWA: Named the appinstalled inline handler so it can be passed to removeEventListener in the effect cleanup
• usePWA: Stored the updatefound handler in a ref (updateFoundHandlerRef) and added a useEffect that removes the listener from the ServiceWorkerRegistration on unmount
• useSearch: Added a useEffect cleanup that clears the pending debounce timer on unmount, preventing a state update on an unmounted component

Test plan

• Mount/unmount a component using usePWA — no appinstalled or updatefound listeners should remain attached
• Type in a search field then unmount quickly — no state-update-on-unmounted-component warning in the console

Closes #190

[drips-wave]

@collinsezedike Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits