fix(web-ui): sync route state with URL hash on mount + hashchange

Added useEffect to parse location.hash and update route state.
Fixes deep links like /#/library not rendering correct screen.

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

services/web-ui/public/app.jsx

@@ -23,6 +23,18 @@ function App() {
       try { localStorage.setItem('df.sidebar.collapsed', next ? '1' : '0'); } catch {}
       return next;
     });
+
+  // Sync route state with URL hash
+  React.useEffect(() => {
+    const parseHash = () => {
+      const hash = window.location.hash.slice(1); // remove #
+      const route = hash.startsWith('/') ? hash.slice(1) : hash || 'home';
+      setRoute(route);
+    };
+    parseHash();
+    window.addEventListener('hashchange', parseHash);
+    return () => window.removeEventListener('hashchange', parseHash);
+  }, []);
   }, []);
 
   React.useEffect(() => {