fix(media): publish status when a track ends naturally

The Redis media:status key was only rewritten after a command received via
Redis. When the last track ended naturally (AudioPlayer Idle -> advanceQueue
with an empty queue), currentTrackItem was cleared but the status key was not
persisted — so the backend's cached status and the frontend's 10s polling
stayed stuck showing the finished track as 'playing' forever.

Wire a media-status sink (commandHandler provides the real redisPub to
MediaHandler) and re-publish status after auto-advance, so natural track end
updates the UI.

services/discord-gateway/src/modules/command-handler/commandHandler.ts

@@ -16,6 +16,7 @@ import {
   createHandlerRegistry,
 } from "./handler-registry.js";
 import { MediaHandler } from "./media.handler.js";
+import { wireMediaStatusWriter } from "./mediaStatusSink.js";
 import { ModerationHandler } from "./moderation.handler.js";
 import { VoiceHandler } from "./voice.handler.js";
 
@@ -88,6 +89,10 @@ export class CommandHandler {
     this.guildHandler = new GuildHandler(client);
     this.moderationHandler = new ModerationHandler(client);
 
+    // Wire the media status sink so MediaHandler can persist status on
+    // queue advances that happen outside a command (natural track end).
+    wireMediaStatusWriter(this.redisPub);
+
     // Build the command registry
     this.registry = createHandlerRegistry(
       this.voiceHandler,