feat(dashboard): add moderation log page + message edit history

- Backend moderation module: GET /api/moderation/stats (per-status + failed rate)
  + GET /api/moderation/actions (filter by status/actionType, cursor paging),
  joins messages for target username + content
- Message GET /api/messages/detail/:id now returns edit_count + edit_history
  (old_content snapshots from message_edits, newest first)
- FE: new /moderation page — summary cards (total/executed/failed/pending +
  failed-rate), status+type filter chips, timeline rows with action icon,
  target user, reason, status badge, timestamps, error text
- FE: message detail shows 'Riwayat edit' panel with previous versions

services/backend/src/modules/messages/messages.repository.ts

@@ -9,6 +9,7 @@ import {
   notInArray,
   or,
   type SQL,
+  sql,
 } from "drizzle-orm";
 import { config } from "../../shared/config/index.js";
 import { getDatabase } from "../../shared/database/index.js";
@@ -114,6 +115,27 @@ export class MessagesRepository {
     return mapMessageRow(row as Record<string, unknown>);
   }
 
+  /**
+   * Edit history for a message: previous content snapshots (newest first).
+   * Stored in message_edits by the gateway's message-capture module.
+   */
+  async getEditHistory(
+    messageId: string,
+  ): Promise<Array<{ old_content: string; edited_at: number }>> {
+    const db = getDatabase();
+    const result = await db.execute(sql`
+      SELECT old_content, edited_at
+      FROM message_edits
+      WHERE message_id = ${messageId}
+      ORDER BY edited_at DESC
+      LIMIT 50
+    `);
+    return ((result.rows as Record<string, unknown>[]) || []).map((r) => ({
+      old_content: String(r.old_content ?? ""),
+      edited_at: Number(r.edited_at ?? 0),
+    }));
+  }
+
   async findByChannel(
     channelId: string,
     query: MessageQuery,

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

@@ -34,7 +34,12 @@ export class MessagesService {
       throw new NotFoundError(`Message with ID ${id} not found`);
     }
 
-    return message;
+    const editHistory = await messagesRepository.getEditHistory(id);
+    return {
+      ...message,
+      edit_count: editHistory.length,
+      edit_history: editHistory,
+    };
   }
 
   async getAttachmentsByChannel(channelId: string, query: MessageQuery) {