feat: Initial commit Plants vs Zombies Web Edition v2.4

- 5 Biomes: Day, Night, Pool, Fog, Roof (25 Campaign levels)
- Minigames: Wall-nut Bowling, I Zombie, Roguelike, Boss Rush & Dr. Zomboss
- Systems: Zen Garden, Workshop Crafting, Almanac, Tree of Wisdom, Achievements
- Backend: REST API + SQLite Accounts & Save Synchronization
- Infrastructure: Nginx HTTPS & Docker deployment

game/js/main.js

@@ -0,0 +1,38 @@
+// Entry point for Plants vs Zombies game
+document.addEventListener('DOMContentLoaded', () => {
+  const startModal = document.getElementById('start-modal');
+  const btnStart = document.getElementById('btn-start');
+
+  const engine = new window.GameEngine('gameCanvas');
+
+  function startGame() {
+    if (startModal) {
+      startModal.classList.add('hidden');
+    }
+    // Initialize Web Audio on user gesture
+    if (window.PvZAudio) {
+      window.PvZAudio.init();
+    }
+    engine.init();
+  }
+
+  if (btnStart) {
+    btnStart.addEventListener('click', startGame);
+  } else {
+    startGame();
+  }
+
+  // Register PWA Service Worker for offline play
+  if ('serviceWorker' in navigator) {
+    window.addEventListener('load', () => {
+      navigator.serviceWorker.register('./sw.js')
+        .then((reg) => {
+          console.log('PvZ ServiceWorker registered:', reg.scope);
+        })
+        .catch((err) => {
+          console.warn('PvZ ServiceWorker registration failed:', err);
+        });
+    });
+  }
+});
+