Driven by the live fresh-eyes finding: a naive racer finishes with 0% paint —
the core mechanic is currently skippable. G makes paint route-guaranteed.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
Fixed-step world runtime, event bus wire protocol between lanes, integration
seam (game.ts) with placeholder ball. Lanes A/B/C own disjoint dirs.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>