[M0-S1] Scaffold Phaser 3 + TypeScript + Vite in game/ #22

Problem

There is no game code yet. Everyone needs the same skeleton before movement or combat can start.

Acceptance criteria

• game/ with Phaser 3.90, TypeScript and Vite; npm run dev shows a 1280×720 canvas
• pixelArt: true, roundPixels, integer scaling to the window where possible
• Scene skeleton: Boot → Preload → Stage (empty) → UI overlay
• npm run build runs tsc --noEmit then vite build; npm run typecheck exists
• npm test runs Vitest; one example test for a pure function
• game/src/core/events.ts: the typed event bus from docs/13 (enemy-defeated, player-hit, player-died, region-turned, boss-defeated, save)
• Placeholders in game/public/assets/placeholder/ at the docs/13 sizes, loaded through the same contracts the real art will use
• game/README.md: install, run, build; Node 22

Notes and dependencies

Stack and folder layout: 08 – Tech stack. Folder names follow the lanes in 12 – Team workflow (src/player, src/combat, src/scenes, …). Owner: Vatsal – lane B, game code (docs/13).

Verification

Fresh clone on a second laptop: dev server and build both work.