feat(worker,ui): Online Inbox config + auth hub plumbing (Phase 2)

Hub: GetOnlineInboxState / SetOnlineInboxConfig / SetOnlineInboxAuth /
ClearOnlineInboxAuth. WorkerConfig.SaveOnlineInbox persists only the
online_inbox section. OnlineTokenStore + config registered always so hub
methods work when sync is disabled. IWorkerClient surface + all test fakes
synced. RedirectUri config (default http://localhost:8765/callback).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

src/ClaudeDo.Worker/Online/OnlineInboxConfig.cs

@@ -25,6 +25,9 @@ public sealed class OnlineInboxConfig
     [JsonPropertyName("poll_interval_seconds")]
     public int PollIntervalSeconds { get; set; } = 60;
 
+    [JsonPropertyName("redirect_uri")]
+    public string RedirectUri { get; set; } = "http://localhost:8765/callback";
+
     [JsonPropertyName("zitadel")]
     public ZitadelClientConfig Zitadel { get; set; } = new();
 }