fix(service-worker): exclude /fonts/ from SW precache

667 font files (~134MB) were being passed to cache.addAll() on every SW
install. cache.addAll() is atomic — a single failed request aborts the
entire install. Browser Cache Storage quota is typically 50-100MB on
mobile, so the SW has likely been silently failing to install on most
mobile devices, negating all caching and the skipWaiting fix.

Only 3 font files are referenced by the browser (app.css). The rest are
badge-print fonts for server/Electron use and do not need to be precached.
The browser's normal HTTP cache handles them when the print page is visited.

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

src/service-worker.js

@@ -6,7 +6,12 @@ const CACHE = `cache-${version}`;
 
 const ASSETS = [
     ...build, // the app itself
-    ...files // everything in `static`
+    // Exclude /fonts/ — 667 font files totalling ~134MB. Only 3 are used by the
+    // browser (app.css); the rest are badge-print fonts for server/Electron use.
+    // cache.addAll() is atomic, so including them would silently abort the entire
+    // SW install on most mobile devices (quota ~50-100MB). The browser's normal
+    // HTTP cache handles font requests when the print page is actually visited.
+    ...files.filter(f => !f.startsWith('/fonts/'))
 ];
 
 self.addEventListener('install', (event) => {