feat: Add service worker for asset caching

- Add Workbox-based service worker to cache JS, CSS, and fonts
- JS/CSS cached for 30 days, fonts for 1 year
- Support for CDN assets via ASSET_CDN_HOST
- Version-based cache invalidation on deployments
- Automatic cache cleanup for old versions
- Build service worker during asset precompilation

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/tasks/build.rake

@@ -5,6 +5,8 @@ task before_assets_precompile: :environment do
   system('pnpm install')
   system('echo "-------------- Bulding SDK for Production --------------"')
   system('pnpm run build:sdk')
+  system('echo "-------------- Building Service Worker --------------"')
+  system('NODE_ENV=production pnpm run build:sw')
   system('echo "-------------- Bulding App for Production --------------"')
 end