Phase 2: auth, session management, layout, PWA manifest

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

web/static/sw.js

@@ -0,0 +1,20 @@
+const CACHE = 'qbank-v1';
+
+self.addEventListener('install', () => self.skipWaiting());
+self.addEventListener('activate', e => e.waitUntil(clients.claim()));
+
+self.addEventListener('fetch', e => {
+  // Network-first: serve fresh, fall back to cache for GET requests.
+  if (e.request.method !== 'GET') return;
+  e.respondWith(
+    fetch(e.request)
+      .then(res => {
+        if (res.ok) {
+          const clone = res.clone();
+          caches.open(CACHE).then(c => c.put(e.request, clone));
+        }
+        return res;
+      })
+      .catch(() => caches.match(e.request))
+  );
+});