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/moderation/moderation.service.ts

@@ -0,0 +1,21 @@
+import { createChildLogger } from "../../shared/logger/index.js";
+import {
+  type ListModerationQuery,
+  moderationRepository,
+} from "./moderation.repository.js";
+
+const logger = createChildLogger("moderation.service");
+
+export class ModerationService {
+  async getStats() {
+    logger.debug("Fetching moderation stats");
+    return moderationRepository.getStats();
+  }
+
+  async listActions(query: ListModerationQuery) {
+    logger.debug({ query }, "Listing moderation actions");
+    return moderationRepository.listActions(query);
+  }
+}
+
+export const moderationService = new ModerationService();