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/threejs-stack.md

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+# Three.js Stack
+
+This is the default non-React 3D runtime stack for the plugin.
+
+## Primary components
+
+- [Three.js documentation](https://threejs.org/docs/) for the core renderer, scene graph, materials, cameras, loaders, and examples.
+- [Rapier JavaScript guide](https://rapier.rs/docs/user_guides/javascript/getting_started_js/) for physics integration.
+- [glTF 2.0 specification](https://registry.khronos.org/glTF/specs/2.0/glTF-2.0.html) for the default shipping asset format.
+- [glTF Transform](https://gltf-transform.dev/) for optimization, packaging, and compression workflows.
+- [SpectorJS](https://spector.babylonjs.com/) for WebGL frame capture and GPU debugging.
+
+## Default stack choices
+
+- Runtime: `three`
+- Tooling: TypeScript + Vite
+- Assets: GLB or glTF 2.0
+- Loaders: `GLTFLoader`, `DRACOLoader`, `KTX2Loader` when the asset pipeline requires them
+- Physics: Rapier JS
+- UI: DOM overlays, not in-scene UI by default
+
+## Choose this stack when
+
+- the project is not React-first
+- the team wants direct control over the render loop
+- scene composition, loader setup, or custom render behavior needs imperative structure
+- the game code should feel engine-like without a React abstraction layer
+
+## Avoid this stack when
+
+- the surrounding app is already React-heavy and wants shared declarative state
+- the project needs an editor-first engine workflow more than a portable TypeScript runtime
+
+## Companion references
+
+- `three-webgl-architecture.md`
+- `threejs-vanilla-starter.md`
+- `gltf-loading-starter.md`
+- `rapier-integration-starter.md`
+- `web-3d-asset-pipeline.md`
+- `webgl-debugging-and-performance.md`