fix(npm): detect musl libc to resolve correct binary on Alpine Linux

[aperkaz]

Description (What)

Adds musl libc detection to the binary resolution logic in npm/index.cjs. On Linux, the launcher now checks /usr/bin/ldd for the presence of "musl" and appends -musl to the optional dependency name when detected, resolving to syncpack-linux-{arch}-musl instead of the glibc variant.

Justification (Why)

On Alpine Linux and other musl-based distros, syncpack fails at runtime with:

Error relocating /node_modules/syncpack-linux-x64/bin/syncpack: __res_init: symbol not found

The glibc-linked binary is resolved because index.cjs has no way to distinguish musl from glibc — it only considers process.platform and process.arch. The musl binary packages (syncpack-linux-x64-musl, syncpack-linux-arm64-musl) are already built and published but were unreachable.

How Can This Be Tested?

• Alpine (musl): Run in an Alpine Docker container — node npm/index.cjs should resolve syncpack-linux-x64-musl

docker run --rm -it -v $(pwd):/app -w /app node:alpine node -e \
  "console.log(require('fs').readFileSync('/usr/bin/ldd','utf8').includes('musl'))"
# → true

• glibc Linux / macOS / Windows: Verify isMusl is false and existing behavior is unchanged
• Missing /usr/bin/ldd: The try/catch returns false, falling back to the glibc package