Story 3: Migrate Service Worker to SvelteKit Native
- Replace workbox imports with SvelteKit $service-worker module
- Use build, files, version arrays for manual cache management
- Implement manual asset caching and cache cleanup
- Replace NavigationRoute with manual fetch handling
- Preserve all push notification event handlers exactly
- Preserve background sync and message handling functionality
- Service worker builds successfully as service-worker.mjs
SvelteKit native implementation ready - now need to enable registration
Refs: docs/plans/MigrateToNativeSvelteKitPWA.md
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