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/lib/navigation.ts

@@ -6,6 +6,7 @@ import {
   Mic,
   Music,
   Search,
+  Shield,
 } from "lucide-react";
 
 export interface NavItem {
@@ -50,6 +51,12 @@ export const navItems: NavItem[] = [
     icon: Headphones,
     matchPrefix: "/recordings",
   },
+  {
+    href: "/moderation",
+    label: "Moderation",
+    icon: Shield,
+    matchPrefix: "/moderation",
+  },
   {
     href: "/analysis",
     label: "Search",