Carnival house rules

Review only the files this pull request changes under src/games/. Report a finding only when the change breaks one of these rules. Quote the line, name the rule, and say what the fix is.

Rules

1. Every game registers on the midway. A game lives in src/games/<game-id>/, exports a CarnivalGame from game.ts, and is added to the list in src/games/index.ts. The folder name and the game's id match. A new game folder with no line in src/games/index.ts, or an id that differs from its folder, is a finding.
2. Every game reports scores through the shared scores module. A game calls recordScore(game.id, score) from src/carnival once, when a round ends. A game that reads or writes localStorage or sessionStorage, keeps its own high score table, or calls recordScore on every frame or more than once per round is a finding.
3. Every game draws with the carnival's theme. Colours, fonts and sizes come from theme and canvasFont in src/carnival/theme.ts. A hex colour, an rgb(/hsl( colour, a named CSS colour or a font string such as '16px sans-serif' inside a game is a finding.
4. Game logic is testable without a browser. Scoring, moving and hits live in plain exported functions that game.test.ts tests. Logic that only exists inside start, or touches document, window, the canvas or requestAnimationFrame outside start, is a finding.
5. start cleans up after itself. It returns a function that cancels the animation frame and removes every listener it added. A listener added with no matching removal, or a frame that is never cancelled, is a finding.
6. Each game has a README that says how to play and how scoring works. A new game with no README.md, or a change to controls or scoring that leaves the README saying something else, is a finding.

Stay quiet on

• Formatting, lint and type errors: npm run check already fails on them.
• Code outside src/games/, and src/games/index.ts beyond rule 1.
• Style preferences that no rule above names.