feat(gateway): add manual video-watch command for selfbot screen-share capture

A selfbot (user token) cannot auto-detect other members' camera/share
(no VOICE_STATE_UPDATE for others, 403 on member fetch). The only
selfbot-viable path to capture another member's SCREEN SHARE is an
operator-initiated STREAM_WATCH (gateway op 20, not gated on bot-vs-user).

Add video:watch / video:unwatch Redis commands routed via the existing
command handler to startStreamWatch/stopStreamWatch, which then does the
DAVE handshake + per-burst MP4 segmentation + DB insert + Tele upload
(already implemented in streamWatchReceiver).

- new VideoHandler (command-handler/video.handler.ts)
- register video:watch / video:unwatch in handler-registry + CommandHandler
- command constants COMMAND_VIDEO_WATCH / COMMAND_VIDEO_UNWATCH
- resolve active voice channel from voice controller + client cache
- 8 unit tests (videoHandler.test.ts)
- biome fixes for pre-existing test import ordering

All green: typecheck, build, lint (174 files), 200 tests.

services/discord-gateway/tests/llmChunkExtraction.test.ts

@@ -34,7 +34,7 @@ describe("extractChunkText — streaming chunk text extraction", () => {
   });
 
   it('falls back to delta.reasoning — mimo via omniroute streams reasoning there with content:""', () => {
-  // Exact shape seen from omniroute → mimo-v2.5-free (2026-08-11):
+    // Exact shape seen from omniroute → mimo-v2.5-free (2026-08-11):
     // {"choices":[{"delta":{"content":"","reasoning":"The user wants a","role":"assistant"},"finish_reason":null,...}]}
     expect(
       extractChunkText({