fix(useSearchParams): cancel debounce before navigation

[ejsmith]

Summary

• cancel a pending useSearchParams debounce timer when SvelteKit navigation begins
• retain the existing component-teardown cleanup
• add a browser regression that queues filter=stale, navigates in-app to filter=fresh, and verifies the old timer cannot overwrite the destination URL

Why

The existing debounce cleanup runs only when the component is destroyed. SvelteKit can navigate while reusing the same route component, leaving the old timer alive. When it fires after the navigation, it can write stale search parameters back onto the new URL.

Registering the same cleanup with beforeNavigate closes that race before the destination navigation starts.

Validation

• pnpm -F runed check
• pnpm -F runed exec vitest --run (246 tests)
• pnpm -F runed exec playwright test src/lib/utilities/use-search-params/use-search-params.scenarios.spec.ts --workers=1 (99 tests)
• pnpm lint

[changeset-bot]

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Latest commit: 23eb766

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