The hardcoded /home/hermes/.local/bin/node doesn't exist in CI runners. Use
shutil.which('node') with a module-level skipif, matching the repo's other
node-driven tests.
The contributor PR had no test for the new helper. Adds Node-driven coverage:
matching-provider prefix stripped, unprefixed untouched, no/mismatched provider
untouched, empty/null passthrough. Co-authored-by: luandnh