fix(reader): support dynamic token-fetcher for foliate PWA caching

Implement a custom callable fetcher function in the Foliate integration that
stringifies to the current auth token. This ensures backward compatibility
for older service-worker cached versions of the Foliate library expecting a
string token, while allowing newer/uncached versions to perform authenticated
requests correctly. Additionally, exclude Foliate assets from PWA precaching
to prevent stale cache bugs on Firefox.

Closes #575

client/vite.config.ts

@@ -79,6 +79,7 @@ export default defineConfig({
       },
       workbox: {
         globPatterns: ['**/*.{js,css,html,ico,png,svg,woff,woff2}'],
+        globIgnores: ['**/assets/foliate/**'],
         navigateFallback: 'index.html',
         navigateFallbackDenylist: [/^\/api\//],
         runtimeCaching: [