fix(auth): fully clear profile on logout (no stale name/gender after sign-out)

The mock service intentionally KEPT the persisted profile (hokm.profile) on
signOut, and getProfile() reloads it — so after logout the previous user's
name/gender/avatar resurrected from localStorage. Now signOut clears the
in-memory + persisted profile, and the SignalR service also clears its mock
fallback so the post-logout guest profile is fresh.

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

src/lib/online/signalr-service.ts

@@ -233,6 +233,7 @@ export class SignalrService implements OnlineService {
     this.token = null;
     this.cachedProfile = null; // drop the signed-in profile so it can't leak post-logout
     if (typeof window !== "undefined") localStorage.removeItem(LS_SESSION);
+    await this.mock.signOut(); // also clear the guest/fallback profile (hokm.profile)
     await this.conn?.stop();
     this.conn = null;
   }