Pre-cache capture and queue pages for offline support

After the SW activates, fetch /capture and /queue in the background
so they are in the runtime cache and available offline immediately
without requiring manual navigation first.

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

app/templates/base.html

@@ -89,6 +89,13 @@
                     .catch((error) => {
                         console.error('Service Worker registration failed:', error);
                     });
+
+                // Pre-cache key pages for offline support once SW is active
+                navigator.serviceWorker.ready.then(() => {
+                    ['/capture', '/queue'].forEach(url => {
+                        fetch(url).catch(() => {});
+                    });
+                });
             });
         } else {
             console.warn('Service Workers not supported in this browser');