feat: add CacheFirst SW rule for attachment images

Attachment images are immutable (UUID-based), so CacheFirst is ideal.
Previously-viewed images remain available offline even after blob URLs
expire. Rule placed before general NetworkFirst API rule to match first.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vite.config.ts

@@ -27,6 +27,14 @@ export default defineConfig({
 				globPatterns: ['client/**/*.{js,css,ico,png,svg,webp,woff,woff2}'],
 				navigateFallback: '/',
 				runtimeCaching: [
+					{
+						urlPattern: /\/api\/notes\/.*\/attachments\?attachmentId=/,
+						handler: 'CacheFirst',
+						options: {
+							cacheName: 'attachment-cache',
+							expiration: { maxEntries: 200, maxAgeSeconds: 365 * 24 * 60 * 60 }
+						}
+					},
 					{
 						urlPattern: /^https?:\/\/.*\/api\//,
 						handler: 'NetworkFirst',