feat: Punkte-Reveal with confetti animation

Shows animated reveal overlay for unseen match results.
Exact match (3pts) triggers confetti explosion.
Each reveal shown only once (localStorage tracking).

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/package.json

@@ -8,12 +8,14 @@
     "preview": "vite preview"
   },
   "dependencies": {
+    "canvas-confetti": "^1.9.4",
     "lucide-react": "^1.7.0",
     "react": "^18.3.1",
     "react-dom": "^18.3.1",
     "react-router-dom": "^6.24.0"
   },
   "devDependencies": {
+    "@types/canvas-confetti": "^1.9.0",
     "@types/react": "^18.3.3",
     "@types/react-dom": "^18.3.0",
     "@vitejs/plugin-react": "^4.3.1",