Single engine now lives on the server. Delete the simulation Web Worker,
the JS mock (mock-wasm), apps/web/public/wasm, and retire WorkerMessageDTO
and the wasm|mock SimulationEngine union from @ymir/types. Drop the
COOP/COEP headers and worker.format from vite config (were only for
in-browser WASM).
Task: task_08. Verified: web typecheck + unit suite green (83%), types
100%, api build clean, no dangling references. E2E against a live server
is validated separately (requires the running apps/api + web).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
