Add self-hosted usage analytics: pageview tracking + admin stats dashboard

Records pageviews (path, referrer, browser/OS/device, IP, GeoIP country) via
a POST /api/track beacon into a new PageView table, and exposes aggregated
daily/breakdown stats behind a token-gated GET /api/admin/stats endpoint with
brute-force lockout. Frontend gets a /admin dashboard (charts + breakdown
tables) built on recharts, with a switchable per-day pageviews chart.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

frontend/package.json

@@ -2,6 +2,7 @@
   "name": "bridzik-frontend",
   "version": "0.1.0",
   "private": true,
+  "type": "module",
   "scripts": {
     "dev": "vite",
     "build": "tsc && vite build",
@@ -12,6 +13,7 @@
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "react-router-dom": "^6.26.0",
+    "recharts": "^2.12.7",
     "socket.io-client": "^4.7.5",
     "zustand": "^4.5.4"
   },