Fix SignalR connection error handling for offline hub

Wrap connection.start() in try/catch so that when the SignalR hub is
unreachable the status transitions to "offline" silently instead of
throwing unhandled errors that flood the browser console.

src/shared/signalr/connection.ts

@@ -141,8 +141,13 @@ export class SignalRConnection {
       this.setStatus("live");
     });
 
-    await this.connection.start();
-    this.setStatus("live");
+    try {
+      await this.connection.start();
+      this.setStatus("live");
+    } catch {
+      // Hub unreachable — go offline silently, don't retry-spam
+      this.setStatus("offline");
+    }
   }
 
   private setStatus(s: ConnectionStatus): void {