Defer OPFS worker termination during open on pagehide (Safari refresh lockups)

[longfellowone]

Issue

Fixes #808

Summary

• Prevents OPFS lock stalls on rapid refresh by deferring worker termination when pagehide fires while open is still in-flight.
• Makes pagehide handling idempotent and ensures a deferred forceClose() runs after open resolves.

Changes

• WASQLiteOpenFactory: pagehide handler now returns early if already triggered; if open is in-flight, it defers termination until after open completes, then forceClose() runs; open failures always terminate the worker.
• WorkerWrappedAsyncDatabaseConnection: keeps forceClose() idempotent via finalizeClose().

Tests

• pnpm --filter @powersync/web run build:tsc
• pnpm vitest --run tests/opfs_pagehide.test.ts
• pnpm vitest (full suite)

Notes

• Pagehide behavior remains consistent regardless of BFCache (event.persisted); change only defers termination during open and ignores repeat pagehide events.

[changeset-bot]

🦋 Changeset detected

Latest commit: 19db84c

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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[longfellowone]

Closing in favor of split PRs