feat(gateway): record others' video via native selfbot watch/receive (Phase C)

Root cause of why Phase A/B captured zero video: @discordjs/voice is audio-only
and never sends the gateway STREAM_WATCH signal, so Discord never forwards a
member's video RTP to the bot. Live diagnostic confirmed: while members were
sharing, audio .ogg files flowed for many users but no non-opus RTP ever
arrived.

Correct path: discord.js-selfbot-v13 ships a complete native watch/record stack.
New src/modules/voice-recording/videoRecorder.ts:
- Detects streamers via voiceState.streaming on a single idempotent
  voiceStateUpdate listener.
- client.voice.joinChannel() (reuses the single session alongside
  @discordjs/voice) + joinStreamConnection(userId) -> STREAM_WATCH (op 20).
- receiver.createVideoStream(userId, path) -> PacketHandler -> Recorder
  (ffmpeg over UDP loopback) -> Matroska .mkv, decryption handled internally.

Wired in recorder.ts (trackChannel/untrackChannel) + bootstrap.ts
(setVideoRecorderClient/setVideoRecordingsDir). All best-effort; failures log
and never break existing voice/audio. Unit tests 6/6 (single listener, watch
handshake + mkv path, skip own video, idempotence, teardown). Full suite
20 files / 176 tests green; typecheck + build + biome clean.

UNVERIFIED live yet: needs deploy + a streamer to confirm Recorder ready +
playable .mkv.

services/discord-gateway/src/app/bootstrap.ts

@@ -36,6 +36,10 @@ import {
   setPcmWsClient,
   setEventBroadcaster as setRecorderEventBroadcaster,
 } from "../modules/voice-recording/recorder.js";
+import {
+  setVideoRecorderClient,
+  setVideoRecordingsDir,
+} from "../modules/voice-recording/videoRecorder.js";
 import { VoiceController } from "../modules/voice-recording/voiceController.js";
 import { config } from "../shared/config/config.js";
 import {
@@ -182,6 +186,12 @@ export async function initializeDiscordGateway() {
   const client = new Client(createDiscordClientOptions());
   const voiceController = new VoiceController(client);
 
+  // Wire the video recorder (others' camera/screen share) to the selfbot's
+  // native watch/receive stack + its recordings dir. Best-effort: failures are
+  // logged inside, never fatal.
+  setVideoRecorderClient(client);
+  setVideoRecordingsDir(config.RECORDINGS_DIR);
+
   // Initialize Redis event broadcaster
   const redisPublisher = new RedisEventPublisher(config.REDIS_URL, logger);
   const eventBroadcaster = new EventBroadcaster(redisPublisher);