Add Radio, Notifications, Moderation plugins with config UI

Plugins page now shows 4 toggleable plugins with config forms:
- Games: in-game mini-game management
- Radio: stream, DJ, song requests with auto-approve/song-limit config
- Notifications: in-app/push/email with retention config
- Moderation Tools: CFH, chat log, ticket config

src/lib/plugins/loader.ts

@@ -1,8 +1,14 @@
 import { pluginRegistry } from "./registry";
 import gamesPlugin from "@/plugins/games";
+import radioPlugin from "@/plugins/radio";
+import notificationsPlugin from "@/plugins/notifications";
+import moderationPlugin from "@/plugins/moderation";
 
 pluginRegistry.register(gamesPlugin);
+pluginRegistry.register(radioPlugin);
+pluginRegistry.register(notificationsPlugin);
+pluginRegistry.register(moderationPlugin);
 
 export function ensurePluginsLoaded(): void {
-	// Plugins loaded at import time
+	// Plugins registered at import time
 }