parallel-cli is a paid third-party vendor skill that requires
PARALLEL_API_KEY, but it was shipped in the default skills/ directory
with no env-var gate. This caused it to appear in every user's system
prompt even when they have no Parallel account or API key.
Move it to optional-skills/ so it is only visible through the Skills
Hub and must be explicitly installed. Also remove it from the default
skills catalog docs.
a99c0478d0