feat(discord-gateway): implement voice & push improvements

- Voice disconnect broadcast on stopRecording
- Multi-guild voice support (VoiceController Map<guildId>)
- Session finalization + auto-enqueue muxer job
- Recordings API: duration field, channelId/userId filters
- Transmitter Redis connection reuse (shared conn)
- FFmpeg stderr memory cap (4KB limit)
- 10 new Redis event channels + Redis bridge subscriptions
- New DB tables: message_reactions, message_edits
- Webhook notification module
- Gateway metrics / Prometheus endpoint
- Multi-guild message capture (MONITOR_GUILD_IDS array)
- Thread tracking, presence, channel topic, guild member events
- Edit history snapshot on message update
- Muxer audio post-processing worker

Co-Authored-By: Claude <noreply@anthropic.com>

services/backend/src/modules/dashboard/dashboard.service.ts

@@ -25,7 +25,11 @@ export class DashboardService {
     return dashboardRepository.getUserDetail(userId);
   }
 
-  async listChannels(query: { limit: number; search?: string; guildId?: string }) {
+  async listChannels(query: {
+    limit: number;
+    search?: string;
+    guildId?: string;
+  }) {
     logger.debug({ query }, "Listing dashboard channels");
     return dashboardRepository.listChannels(query);
   }