feat(gmw): public features #2-#6 — live moderation feed, toxic topic trends, channel timeline, CSV export, activity heatmap

- Live Moderation Feed: gateway publishes discord:moderation:action (Redis) → backend WS emits moderation_action → public web shows realtime stream.
- Toxic Topic Trends: backend moderation.trends aggregates categories/severity/action_type (read-only) → SVG bar + donut.
- Channel Timeline: messages view gets Feed/Timeline toggle with date-grouped separators.
- CSV Export: client-side downloadCsv for moderation actions (no backend write scope).
- Activity Heatmap: backend messages.activity (per-hour volume by channel) → pure-SVG grid.

User reputation deliberately excluded — no such feature exists in the codebase.
All read-only / public-facing / fully automatic per project rules.

services/discord-gateway/src/modules/event-broadcaster/eventBroadcaster.ts

@@ -293,6 +293,16 @@ export class EventBroadcaster {
     });
   }
 
+  async moderationAction(data: Record<string, unknown>): Promise<void> {
+    this.logger.debug({ data }, "Publishing moderation_action");
+    await this.publisher.publish(EventChannels.MODERATION_ACTION, {
+      type: "moderation_action",
+      data,
+      timestamp: Date.now(),
+      source: "discord-gateway",
+    });
+  }
+
   async analysisQueueStatus(data: Record<string, unknown>): Promise<void> {
     this.logger.debug({ data }, "Publishing analysis_queue_status");
     await this.publisher.publish(EventChannels.ANALYSIS_QUEUE_STATUS, {

services/discord-gateway/src/modules/event-broadcaster/eventTypes.ts

@@ -9,6 +9,7 @@ import {
   DISCORD_MESSAGE_CREATED,
   DISCORD_MESSAGE_DELETED,
   DISCORD_MESSAGE_UPDATED,
+  DISCORD_MODERATION_ACTION,
   DISCORD_PRESENCE_UPDATED,
   DISCORD_REACTION_ADDED,
   DISCORD_REACTION_REMOVED,
@@ -50,6 +51,7 @@ export const EventChannels = {
   GUILD_MEMBER_ADDED: DISCORD_GUILD_MEMBER_ADDED,
   GUILD_MEMBER_REMOVED: DISCORD_GUILD_MEMBER_REMOVED,
   VOICE_ANALYZED: DISCORD_VOICE_ANALYZED,
+  MODERATION_ACTION: DISCORD_MODERATION_ACTION,
 } as const;
 
 export type EventChannelType =