fix: correct riscv64 package metadata and CI target

[AvrovaDonz2026]

The riscv64 prebuilt integration is already wired through the build, packaging, and runtime paths, but two release-path issues remain:

• The standalone riscv64 package lockfile incorrectly records CPU compatibility as arm/x64, while package.json correctly declares riscv64. npm consumers can therefore resolve or reject the package using stale metadata.
• The CI buildBinary helper accepts a nodeTarget argument but always passes nodeVersion, so a requested Node ABI target is ignored.

This change aligns the lockfile with the riscv64 package manifest and passes the selected Node target through to source build.

Validation:

• git diff --check
• package manifest and lockfile metadata consistency check
• riscv64 CI matrix/build wiring check

The full TypeScript/native build requires dependencies and a riscv64 runner, so it was not run in this local x64 checkout.