Initial commit: Game Maker phase 1

Canvas-only 2D game editor/runtime built on PixiJS v8 + Vite + TypeScript.

- core: asset model (Scene/Camera/Sprite), scene objects with sparse
  overrides, property schema + resolve, command stack (undo/redo),
  serialization and project store interface (16 unit tests)
- ui: custom in-canvas widget toolkit (panels, fields, color picker,
  list/scroll, popup) with a hidden <input> keyboard bridge
- editor: asset/hierarchy panels, schema-driven inspector, toolbar
- viewport: box rendering, camera frame, selection gizmo, drag/zoom/pan
- runtime: world/entity instantiation for play mode, input, camera follow
- api: PHP JSON project store with revision counter (409 on conflict)
- tools: CDP-based e2e smoke test

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

tsconfig.json

@@ -0,0 +1,20 @@
+{
+  "compilerOptions": {
+    "target": "ES2022",
+    "module": "ESNext",
+    "moduleResolution": "bundler",
+    "lib": ["ES2022", "DOM", "DOM.Iterable"],
+    "strict": true,
+    "noUncheckedIndexedAccess": true,
+    "noImplicitOverride": true,
+    "noUnusedLocals": true,
+    "noUnusedParameters": true,
+    "noFallthroughCasesInSwitch": true,
+    "isolatedModules": true,
+    "skipLibCheck": true,
+    "esModuleInterop": true,
+    "resolveJsonModule": true,
+    "types": ["vite/client", "node"]
+  },
+  "include": ["src", "tests", "vite.config.ts"]
+}