hermes plugins validate --install-deps synced the plugin's declared
dependencies into a newly committed environment, then ran the capability
probe with sys.executable, the pre-sync interpreter. Plugins importing a
non-core package at load time (evalroute: pyyaml, gone from core since the
ruamel move) failed the catalog gate with a masked ImportError.
Run the probe with the committed environment's interpreter and activation
env. A developer venv without a committed environment keeps the old path.
48de727da5