Per ADR-005 tests run against the real WASM engine, so CI must build it
first. Add a wasm-web job: pinned emsdk (cached) -> pnpm build:wasm ->
build -> lint -> test. Wire turbo so 'test' dependsOn build:wasm and
^build:wasm, and point build:wasm outputs at the @ymir/wasm runtime.
Task: task_09. Verified turbo ordering locally (rm runtime -> turbo test
rebuilds it); full pipeline runs on GitHub Actions.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
