Initial commit: Tetris Battle Royale multiplayer game

Features:
- 2-8 player multiplayer via Socket.io WebSocket
- Real-time board synchronization - all players see all boards
- Battle royale mechanic: clearing rows sends garbage to opponents
- Classic Tetris gameplay with all 7 tetrominoes
- Retro visual styling with CRT scanlines and pixel font
- Automatic level progression and speed increase
- Player elimination and winner announcement

Files:
- server/index.js: Node.js + Socket.io game server
- public/js/: Frontend game logic, rendering, network, and UI
- public/css/style.css: Retro Tetris styling
- README.md: Setup and usage instructions
- PLAN.md: Implementation plan with all phases completed

server/package.json

@@ -0,0 +1,15 @@
+{
+  "name": "tetris-battle-royale",
+  "version": "1.0.0",
+  "description": "Multiplayer Tetris Battle Royale",
+  "main": "index.js",
+  "scripts": {
+    "start": "node index.js",
+    "dev": "node index.js"
+  },
+  "dependencies": {
+    "express": "^4.18.2",
+    "socket.io": "^4.7.2",
+    "uuid": "^9.0.0"
+  }
+}