Main window: Main, Settings, Statistics and Tools tabs as a markup panel

The original's notebook without the parts OpenAC or another plugin now owns
(updater, VTank path, route visualisation, chest looter). Labels read live
from the trackers each frame. Settings gains the backend URL and shared-secret
fields, since the secret is no longer compiled in. Tools opens the Mossy
Tracker and Metas windows through openers their features set. The WebSocket
label now shows the real connection state rather than the setting.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/OpenAC.MosswartMassacre/FeatureCatalog.cs

@@ -27,6 +27,7 @@ internal static class FeatureCatalog
         features.Add(new VitalsStream(context));
         features.Add(new SpawnPortalStream(context));
         features.Add(new BotControl(context));
+        features.Add(new Views.MainWindow(context, stats));
         session.AddConnectionListener(telemetry);
     }
 }