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/frontend/src/shared/api/client.ts

@@ -281,7 +281,11 @@ export interface DashboardStats {
   today_messages: number;
   today_flagged: number;
   active_users_24h: number;
-  top_channels: Array<{ channel_id: string; channel_name: string | null; message_count: number }>;
+  top_channels: Array<{
+    channel_id: string;
+    channel_name: string | null;
+    message_count: number;
+  }>;
   moderation_overview: {
     pending: number;
     processing: number;