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/three-webgl-architecture.md

@@ -0,0 +1,61 @@
+# Three WebGL Architecture
+
+This is the default 3D structure for the plugin.
+
+## Recommended module split
+
+```text
+src/
+  game/
+    simulation/
+    content/
+    input/
+    save/
+  render/
+    app/
+      createRenderer.ts
+      createScene.ts
+      createCamera.ts
+      createLoop.ts
+    loaders/
+      loadGltf.ts
+      loadEnvironment.ts
+      loadTextures.ts
+    objects/
+    materials/
+    lights/
+    post/
+    adapters/
+      renderBridge.ts
+  physics/
+    world.ts
+    colliders.ts
+    sync.ts
+  diagnostics/
+    debugFlags.ts
+    perf.ts
+  ui/
+    hud/
+    menus/
+    overlays/
+```
+
+## Responsibilities
+
+- `simulation/`: rules, state, AI, progression, save data
+- `render/app/`: renderer, scene, camera, resize, context lifecycle
+- `render/loaders/`: GLTF, compression, texture, and environment loading
+- `render/objects/`: scene graph construction and disposal
+- `render/materials/`: material setup and shader boundaries
+- `physics/`: Rapier world and simulation bridge
+- `diagnostics/`: performance probes and GPU debugging hooks
+- `ui/`: DOM HUD and menus
+
+## Rules
+
+- Scene graph objects are not the source of truth for game rules.
+- Keep camera logic explicit and testable.
+- Handle resize and context-loss as real browser concerns.
+- Keep high-density UI in DOM even when the world is fully 3D.
+- Treat GLB or glTF 2.0 as the default content format.
+- Add physics and diagnostics as real subsystems, not temporary one-off utilities.