build-bindings.ts built the failure error from captured stderr only, but
napi-rs/cargo route much of the failure detail to stdout (e.g. `cargo
metadata exited with code 101 ...`). When stderr was empty the thrown
error collapsed to a bare "napi build failed", hiding the real cause.
Attach the exit code plus tail-capped stdout and stderr sections to the
thrown error so the actionable output survives on the error object.
Fixes#6796
roboomp
550f3e9d19