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>

README.md

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+# Game Maker
+
+A browser-based tool "one step before a game engine": create **assets** (scenes, cameras,
+sprites), place them into scenes, tweak their properties in an inspector and press **Play** –
+all in one program, all drawn inside a single WebGL canvas.
+
+Live: <https://nockal.com/game-maker/> · Widget playground: <https://nockal.com/game-maker/?playground>
+
+## Concepts
+
+| Term | Meaning |
+|---|---|
+| **Asset** | Named thing with a type (`scene`, `camera`, `sprite`) and typed properties. Assets have **no position**. |
+| **Scene object** | An asset placed into a scene: a link to the asset + a **position** + sparse **overrides** of the asset's properties. Scenes cannot be placed. |
+| **Override** | A per-object value that replaces the asset's value for one property. Only changed keys are stored; the inspector marks them bold and offers a reset (↺). |
+| **Edit mode** | The viewport draws the project model; panels, grid, gizmos and drag-to-move are active. |
+| **Play mode** | A `World` is instantiated from the active scene (one entity per scene object, resolved properties as mutable state). Systems tick it; nothing writes back. **Stop discards the world.** |
+
+Phase-1 demo behaviour in Play: the arrow keys move the sprite that was selected when Play was
+pressed (or the first sprite); the first camera in the scene follows it.
+
+## Stack
+
+- **PixiJS v8** – rendering and pointer events. No game engine; runtime systems live in `src/runtime/`.
+- **Own canvas widget toolkit** (`src/ui/`) – panels, buttons, lists, text/number/color fields,
+  popups. The only DOM element is a hidden `<input>` used as a keyboard bridge (IME, mobile
+  keyboard, clipboard) while a canvas text field is focused.
+- **Vite + TypeScript**, **Vitest** for the pure core.
+- **PHP 8** JSON API (`api/`) storing one JSON file per project in `data/projects/`, with
+  atomic writes and an integer revision that rejects stale saves (HTTP 409).
+
+## Layout
+
+```
+web/index.html      Vite source page (dev)            index.html   built page (generated, served)
+src/core/           model, property schema, resolve, commands, store – no Pixi imports
+src/runtime/        World, Entity, systems (Input, PlayerControl, CameraFollow)
+src/ui/             widget toolkit (generic, knows nothing about assets)
+src/viewport/       scene renderer: model in edit mode, world in play mode
+src/editor/         App composition, state, panels, inspector field factory
+api/                PHP backend            data/projects/   persisted projects
+tests/              Vitest unit tests      tools/e2e.mjs    headless CDP smoke test
+```
+
+Rules that keep it organised: `core/` imports nothing from other layers; `ui/` never sees
+assets; position exists only on scene objects; overrides are merged in exactly one place
+(`core/properties/resolve.ts`); the inspector is generated from `PropertySchema` – a new
+property is one schema line.
+
+## Development
+
+Node 22 is required (on this machine: `PATH=/opt/node22/bin:$PATH`).
+
+```bash
+npm install
+npm run dev          # http://localhost:5175/game-maker/dist/ – API calls are proxied to production
+npm test             # unit tests (core)
+npm run typecheck
+npm run build        # writes dist/ and regenerates index.html
+node tools/e2e.mjs <projectId>   # headless end-to-end run with screenshots in /tmp/gm-e2e-*.png
+```
+
+The workspace folder itself is what nginx serves, so `npm run build` is the deployment.
+
+## API
+
+All routes go through `api/index.php?r=…` (the site's nginx does not pass `PATH_INFO`).
+
+| Method | Route | Body → Result |
+|---|---|---|
+| GET | `projects` | `[{id,name,revision,updatedAt}]` |
+| POST | `projects` | `{name}` → project document (201) |
+| GET | `projects/{id}` | `{id,name,revision,updatedAt,project}` |
+| PUT | `projects/{id}` | `{revision, project}` → `{revision,updatedAt}` or **409** `{revision}` when stale |
+| DELETE | `projects/{id}` | 204 |
+
+There is no authentication yet; `data/` is world-readable. Both are phase-2 topics.
+
+## Keyboard
+
+`Ctrl+Z` / `Ctrl+Shift+Z` / `Ctrl+Y` undo/redo · `Delete` remove selection · `Ctrl+Enter` play ·
+`Esc` stop · `Tab` cycles fields · number fields: drag to scrub (`Shift` ×10, `Alt` ×0.1),
+`↑`/`↓` step · viewport: wheel zooms, middle-drag or `Shift`+drag pans.
+
+## Out of scope for phase 1
+
+Textures on sprites, physics, scripting, multi-select, z-order UI, auth, editing while playing,
+touch-optimised layout.