feat: add analytics hooks and routes for moderation statistics

- Implemented `useAnalytics` hook for fetching and managing analytics data.
- Created `analyticsStore.ts` to handle database queries for hourly stats, topic trends, user leaderboard, and moderation stats.
- Added Express routes for analytics endpoints including overview, hourly stats, topic trends, user leaderboard, moderation stats, and top violators.
- Introduced a utility function `filterHits` for filtering specific terms in text.

frontend/src/components/layout/Header.tsx

@@ -9,6 +9,7 @@ const titles: Record<DashboardTab, string> = {
   media: "Media Player",
   messages: "Messages",
   recordings: "Voice Recordings",
+  analytics: "Analytics & Insights",
   review: "Moderation Review",
 };
 

frontend/src/components/layout/Sidebar.tsx

@@ -1,4 +1,4 @@
-import { Bot, MessageSquare, Music2, ShieldAlert, Volume2, Mic } from "lucide-react";
+import { Bot, BarChart3, MessageSquare, Music2, ShieldAlert, Volume2, Mic } from "lucide-react";
 import type { DashboardTab } from "../../types/ui";
 import { cn } from "../../lib/utils";
 import { Button } from "../ui/button";
@@ -8,6 +8,7 @@ const navItems: Array<{ id: DashboardTab; label: string; icon: typeof Volume2 }>
   { id: "media", label: "Media", icon: Music2 },
   { id: "messages", label: "Messages", icon: MessageSquare },
   { id: "recordings", label: "Recordings", icon: Mic },
+  { id: "analytics", label: "Analytics", icon: BarChart3 },
   { id: "review", label: "Review", icon: ShieldAlert },
 ];