refactor: remove voice, recording, and music/media features (gateway + backend)

- Gateway: delete voice-recording/, voice-pcm-ws/, voice/video/media handlers,
  vendor/discord-voice-fork/, voice DB repos, 2 voice migrations
- Gateway: cut voice wiring from bootstrap/shutdown/commandHandler/handler-registry,
  eventBroadcaster/eventTypes, redis-channels, moderation-types, message-capture,
  config keys, and deps (@discordjs/voice, opus, libsodium, prism-media, davey)
- Backend: delete voice/, recordings/, media/ modules + @discordjs/voice dep
- Backend: cut voice/media/recordings oRPC routers, WS gateway-PCM auth + voice
  handlers, Redis bridge voice aggregation, redis-channels voice/media constants,
  config keys, moderation-types voice items, e2e voice/recordings suites
- Keep voice DB tables (destructive migration avoided); chatbot voiceRecordings
  tool + dashboard count remain as read-only historical data access

services/discord-gateway/drizzle/migrations/0011_add_voice_transcription.sql

@@ -1 +0,0 @@
-ALTER TABLE "voice_recordings" ADD COLUMN "transcription" text;

services/discord-gateway/drizzle/migrations/0020_add_voice_auto_reconnect.sql

@@ -1,19 +0,0 @@
--- Voice auto-reconnect: persist desired voice state per guild.
--- The gateway rejoins the same channel after restart/reboot and after an
--- unexpected voice drop (kick / server move / voice server restart).
--- Idempotent: skips if the table already exists.
-DO $$
-BEGIN
-  IF NOT EXISTS (
-    SELECT 1 FROM information_schema.tables
-    WHERE table_name = 'voice_auto_reconnect'
-  ) THEN
-    CREATE TABLE "voice_auto_reconnect" (
-      "guild_id" text PRIMARY KEY NOT NULL,
-      "channel_id" text NOT NULL,
-      "channel_name" text,
-      "connected_at" bigint NOT NULL,
-      "updated_at" bigint NOT NULL
-    );
-  END IF;
-END $$;

services/discord-gateway/drizzle/migrations/meta/_journal.json

@@ -79,13 +79,6 @@
       "tag": "0010_add_reactions_and_edit_history",
       "breakpoints": true
     },
-    {
-      "idx": 11,
-      "version": "7",
-      "when": 1785600000000,
-      "tag": "0011_add_voice_transcription",
-      "breakpoints": true
-    },
     {
       "idx": 12,
       "version": "7",
@@ -141,13 +134,6 @@
       "when": 1787830000000,
       "tag": "0019_rename_server_name_to_server_nick",
       "breakpoints": true
-    },
-    {
-      "idx": 20,
-      "version": "7",
-      "when": 1787860000000,
-      "tag": "0020_add_voice_auto_reconnect",
-      "breakpoints": true
     }
   ]
 }