fix(auth, pwa): restore api.auth.me, bump PWA cache to v5.3, and fix CEFR CSS styling

app/static/sw.js

@@ -1,7 +1,7 @@
 // Service Worker for Notes English PWA (Stage 2)
 // Strategy: Cache-first for static assets, Network-first for API calls.
 
-const CACHE_NAME = 'notes-v5.2';
+const CACHE_NAME = 'notes-v5.3';
 const OFFLINE_URL = '/';
 
 const PRECACHE_URLS = [
@@ -67,14 +67,14 @@ self.addEventListener('fetch', (event) => {
     return;
   }
 
-  // Static assets (CSS, JS, icons) → Cache-first
+  // Static assets (CSS, JS, icons) → Cache-first (with ignoreSearch)
   if (
     url.pathname.startsWith('/static/') ||
     url.pathname === '/manifest.json' ||
     url.pathname === '/sw.js'
   ) {
     event.respondWith(
-      caches.match(request).then((cached) => {
+      caches.match(request, { ignoreSearch: true }).then((cached) => {
         return cached || fetch(request).then((response) => {
           if (response.ok) {
             const clone = response.clone();