Add a mini game to the portal

The portal and the Rsbuild config discover games from src/games/<id>/game.json. No central registry needs editing.

Steps

1. Pick a short id ([a-z0-9_-]), create src/games/<id>/.
2. Write game.json (schema: src/portal/manifest.ts):

   {
     "id": "<id>",
     "title": "My Game",
     "version": "0.1.0",
     "description": "One or two sentences for the portal card.",
     "tags": ["three.js"],
     "pages": [
       {
         "id": "play",
         "entry": "pages/play.ts",
         "title": "My Game",
         "label": "Play"
       },
       {
         "id": "level-viewer",
         "entry": "pages/level-viewer.ts",
         "title": "My Game · Levels",
         "label": "Levels",
         "dev": true
       }
     ]
   }
   

   • play is served at /games/<id>/; other pages at /games/<id>/<page-id>.html.
   • dev: true pages show as tool buttons on the portal card.
   • Links must be relative (the build may be hosted in a sub-folder): portal = ../../, sibling page = <page-id>.html, main page = ./. Never use a leading /.
   • The game builds into its own self-contained dist/games/<id>/ (own Rsbuild environment, picked up automatically). Load runtime files relative to the page (new URL('models/x.glb', location.href)) or import them, never from the portal root; a game-only file in the root public/ needs a gamePublicFiles entry in rsbuild.config.ts.
   • The play page's main menu (and pause / results screens) must offer an All games button when portalUrl() (src/shared/portal-link.ts) is not null - installed as a PWA there is no browser back button.
3. Entry files: the default HTML template has <div id="root">. Import page CSS from the entry. Use three.js unless the user asked otherwise. Reuse src/shared/*:
   • debug-panel.ts (left tool menu), url-state.ts (bookmarkable state), stats-overlay.ts (F3)
   • rng.ts / noise.ts for anything procedural (seeded!)
4. Portal screenshot: in the play page call installThumbnailCapture('<id>', () => { renderer.render(scene, camera); return renderer.domElement; }), run npm run dev, open the game, press F9 -> writes src/games/<id>/thumbnail.jpg.
   • Audio: the game's audio class (WebAudio / Audio) must start silent when isMutedByUrl() (src/shared/mute-param.ts, ?mute=1) is true. When you open the game in the browser pane to test, always add mute=1 to the URL - no sound while creating / editing, unless the task is a sound fix (then no param, low volume).
5. Add the game to GAME_LIST in src/portal/release.ts (card order). Work in progress? Give it hideInProd: true there: the release build gives the game no portal card but still builds it, so people with the link (games/<id>/) can play it. The dev server and build:test list it. Remove the flag to release.
6. Restart npm run dev after adding a new game folder / page (entries are read at startup).
7. Tests in tests/<id>/, a test:<id> npm script and a CI job (testing skill); keep game logic DOM-free so it is testable in node.
8. Write the docs short (AGENTS.md "Write short"). Add src/games/<id>/README.md (high level: what it is, screenshot, how to play, feature list, links) and src/games/<id>/DETAILS.md (pages, keys, rules, architecture), and a row in the root README.md table.
9. Verify: npx tsc --noEmit -p tsconfig.json, npm run lint, npm run test, npm run build.

Patterns worth copying from rally

• Fixed-step simulation + render interpolation (src/games/rally/game/rally-game.ts).
• benchmark(n) method exposed on window.__<game> to measure ms/frame even when the tab is hidden.
• Tool pages built on a shared shell (src/games/rally/debug/viewer-shell.ts).