Initial release: game-studio plugin for Claude Code

Repackaged from OpenAI's game-studio Codex plugin (MIT) for Claude Code.

Changes from upstream:
- Added .claude-plugin/plugin.json (Claude Code plugin manifest)
- Removed .codex-plugin/plugin.json (Codex CLI specific)
- Removed skills/*/agents/openai.yaml (Codex CLI specific)
- Added scripts/requirements.txt (Pillow dependency for sprite-pipeline)
- Added Chinese README with installation guide

references/gltf-loading-starter.md

@@ -0,0 +1,43 @@
+# GLB Loading Starter
+
+Use this as the canonical minimal pattern for loading shipped 3D content.
+
+## Vanilla Three.js
+
+```ts
+import { GLTFLoader } from "three/examples/jsm/loaders/GLTFLoader.js";
+import { DRACOLoader } from "three/examples/jsm/loaders/DRACOLoader.js";
+
+const draco = new DRACOLoader();
+draco.setDecoderPath("/draco/");
+
+const gltfLoader = new GLTFLoader();
+gltfLoader.setDRACOLoader(draco);
+
+gltfLoader.load("/assets/hero.glb", (gltf) => {
+  const root = gltf.scene;
+  root.traverse((node) => {
+    if ("castShadow" in node) {
+      node.castShadow = true;
+      node.receiveShadow = true;
+    }
+  });
+  scene.add(root);
+});
+```
+
+## React Three Fiber
+
+```tsx
+import { useGLTF } from "@react-three/drei";
+
+function HeroModel() {
+  const gltf = useGLTF("/assets/hero.glb");
+  return <primitive object={gltf.scene} />;
+}
+```
+
+## Notes
+
+- Default shipping format is GLB or glTF 2.0.
+- Keep optimization upstream in the asset pipeline; loader code should stay boring.