Linux ORT glibc detection

Trap: mapping native ONNX Runtime by linux-<arch> looks sufficient because npm already gates packages by OS and CPU, but the shipped addon requires libc.so.6 and GLIBC symbols and will be selected on musl. Fix: distinguish glibc from musl before release-package or workspace resolution and return null on unsupported libc, because loader failure after native commitment does not automatically fall back to WASM.