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/frontend/src/app/(dashboard)/moderation/page.tsx

@@ -0,0 +1,11 @@
+"use client";
+
+import { ModerationSection } from "@/components/moderation/moderation-section";
+
+export default function ModerationPage() {
+  return (
+    <div className="space-y-4 animate-fade-in-up">
+      <ModerationSection />
+    </div>
+  );
+}