fix(web): remove unload event listener to fix Chrome 146+ deprecation

[JexanJoel]

Fixes #912

Based on maintainer feedback in #912, the unload event listeners have been removed entirely rather than replaced with pagehide.

pagehide is not appropriate here because close() is a terminal action - if the tab is restored from bfcache, the database would remain closed.

Since navigator locks now reliably handle tab detection, the unload listeners are no longer needed.

Changes in packages/web/src/db/PowerSyncDatabase.ts:

• Removed unloadListener property
• Removed window.addEventListener('unload', ...) block from constructor
• Removed window.removeEventListener('unload', ...) block from close()

[changeset-bot]

🦋 Changeset detected

Latest commit: a0eba9c

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@powersync/web	Patch
@powersync/diagnostics-app	Patch

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[JexanJoel]

Based on the discussion in #912, I've removed the unload listeners entirely since navigator locks now handle tab detection. Happy to revert or adjust if more testing is needed before this is merged.

[simolus3]

I ran a quick manual test of these changes in the react supabase todolist demo app. Closing a tab providing the database for the sync worker still makes it retry with a different tab, so it looks like the unload listeners indeed aren't necessary anymore.

I'd like to wait for Steven to also take a look once he's back, in case he finds additional issues to look out for.

[simolus3]

Thanks for your contribution!

[JexanJoel]

Thank you! Happy to contribute to PowerSync 🙌