feat: implement Suika Game (Watermelon Game)

Browser-based physics puzzle game where players drop fruits that merge
into larger fruits on collision, using Matter.js for 2D physics and
Canvas2D for rendering. Includes 11-fruit progression chain, scoring,
game-over detection, mouse/touch input, and Vitest test suite.

package.json

@@ -0,0 +1,20 @@
+{
+  "name": "suika-game",
+  "version": "1.0.0",
+  "private": true,
+  "type": "module",
+  "scripts": {
+    "dev": "vite",
+    "build": "vite build",
+    "preview": "vite preview",
+    "test": "vitest run",
+    "test:watch": "vitest"
+  },
+  "devDependencies": {
+    "vite": "^8.0.4",
+    "vitest": "^4.1.4"
+  },
+  "dependencies": {
+    "matter-js": "^0.20.0"
+  }
+}