Mirrors the workflow in fai/platform: Linux x86_64 only, manual
checkout via the external URL to bypass DinD network isolation,
fmt/clippy/build/test on host, plus an explicit wasm32-wasip2
release build to confirm the module still produces a valid WASM
component.
See fai/platform docs/architecture/ci.md for the rationale on
why we don't use actions/checkout.
Signed-off-by: flemming-it <sf@flemming.it>
