Fix SW scope to intercept page navigations for offline support

The SW was served from /static/sw.js with default scope /static/,
so it only intercepted static asset requests. Page navigations to
/capture, /queue, /browser were not handled by the SW at all —
Safari showed its native offline error.

Fix: serve SW from /sw.js route with Service-Worker-Allowed: / header
and register with scope: /. Now the SW intercepts all navigations and
serves the offline fallback page when the network is unavailable.

Also remove auth-protected page routes from precache (they would cache
the login redirect). Pages are cached via network-first on visit instead.

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

app/templates/base.html

@@ -65,7 +65,7 @@
     <script>
         if ('serviceWorker' in navigator) {
             window.addEventListener('load', () => {
-                navigator.serviceWorker.register('/static/sw.js')
+                navigator.serviceWorker.register('/sw.js', { scope: '/' })
                     .then((registration) => {
                         console.log('Service Worker registered:', registration.scope);