fix(ui): no-cache static assets (stop stale CSS/JS after deploys); live nav-active sync; breadcrumb sized+themed to match back button

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

server.js

@@ -20,7 +20,11 @@ export function createApp() {
     limit: '10mb',
     verify: (req, _res, buf) => { req.rawBody = buf; }
   }));
-  app.use(express.static('public'));
+  // no-cache (not no-store): the browser may cache but must revalidate, so a
+  // deploy's new CSS/JS takes effect immediately instead of serving stale assets.
+  app.use(express.static('public', {
+    setHeaders: (res) => res.setHeader('Cache-Control', 'no-cache')
+  }));
 
   // /api/ingest/* bypasses agentOrOwner — webhooks authenticate via HMAC
   // and need access to req.rawBody captured above.