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/ws/redis-bridge.ts

@@ -2,10 +2,19 @@ import {
   DISCORD_ANALYSIS_QUEUE_STATUS,
   DISCORD_ATTACHMENT_CREATED,
   DISCORD_ATTACHMENT_UPLOADED,
+  DISCORD_CHANNEL_TOPIC_UPDATED,
+  DISCORD_GUILD_MEMBER_ADDED,
+  DISCORD_GUILD_MEMBER_REMOVED,
   DISCORD_MESSAGE_ANALYZED,
   DISCORD_MESSAGE_CREATED,
   DISCORD_MESSAGE_DELETED,
   DISCORD_MESSAGE_UPDATED,
+  DISCORD_PRESENCE_UPDATED,
+  DISCORD_REACTION_ADDED,
+  DISCORD_REACTION_REMOVED,
+  DISCORD_THREAD_CREATED,
+  DISCORD_THREAD_DELETED,
+  DISCORD_THREAD_UPDATED,
   DISCORD_VOICE_ACTIVE_USER,
   DISCORD_VOICE_PCM,
   DISCORD_VOICE_STARTED,
@@ -40,6 +49,18 @@ const SUBSCRIPTIONS: ChannelMapping[] = [
   },
   { channel: DISCORD_VOICE_ACTIVE_USER, eventType: "voice_active_user" },
   { channel: DISCORD_VOICE_PCM, eventType: "voice_pcm_data" },
+  { channel: DISCORD_REACTION_ADDED, eventType: "reaction_added" },
+  { channel: DISCORD_REACTION_REMOVED, eventType: "reaction_removed" },
+  { channel: DISCORD_THREAD_CREATED, eventType: "thread_created" },
+  { channel: DISCORD_THREAD_DELETED, eventType: "thread_deleted" },
+  { channel: DISCORD_THREAD_UPDATED, eventType: "thread_updated" },
+  {
+    channel: DISCORD_CHANNEL_TOPIC_UPDATED,
+    eventType: "channel_topic_updated",
+  },
+  { channel: DISCORD_PRESENCE_UPDATED, eventType: "presence_updated" },
+  { channel: DISCORD_GUILD_MEMBER_ADDED, eventType: "guild_member_added" },
+  { channel: DISCORD_GUILD_MEMBER_REMOVED, eventType: "guild_member_removed" },
 ];
 
 let subscriber: Redis | null = null;