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/webgl-debugging-and-performance.md

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+# WebGL Debugging and Performance
+
+Use this reference when a browser 3D scene is visually wrong, unstable, or slower than expected.
+
+## Primary tools
+
+- [SpectorJS](https://spector.babylonjs.com/) for frame capture, pipeline inspection, draw-call review, and shader debugging.
+- Browser performance tooling for main-thread work, asset decode stalls, and memory pressure.
+- Engine-native debug views and stats surfaces where available.
+
+## What to inspect first
+
+- draw-call count
+- shader compilation churn
+- texture memory pressure
+- geometry count and material count
+- post-processing cost
+- asset decode and streaming stalls
+- WebGL context loss or fallback behavior
+
+## Common causes of poor performance
+
+- too many unique materials
+- oversized textures
+- heavy GLB assets loaded without optimization
+- complex post-processing on top of an already expensive scene
+- physics and render state fighting for ownership
+- React and scene state updating each other too frequently in React-hosted 3D apps
+
+## Debugging rules
+
+- Capture first, then guess.
+- Reduce the scene until the perf cliff becomes obvious.
+- Disable post-processing before rewriting core scene code.
+- Verify the asset pipeline before blaming the renderer.
+- Treat context-loss handling as a browser requirement, not an edge case.