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.

.claude/settings.json

@@ -1,4 +1,10 @@
 {
+  "permissions": {
+    "allow": [
+      "Bash(claudekit *)",
+      "Bash(claudekit-hooks *)"
+    ]
+  },
   "hooks": {
     "PreToolUse": [
       {