V3 deterministic CSV validation capability pack. By-value connector composition (service_kind=cli, no separate ingredient): the local csvclean CLI validates one CSV file via the csv.validate catalog operation. This pack deliberately exposes a safe validator only: csvkit's transform tools mostly write transformed content to stdout, which is not a good fit for file_ref materialization and content-isolation. The operation materializes the source file, runs fixed csvclean structural checks, and captures no stdout/stderr value. Requires csvkit on PATH (Debian/Ubuntu: apt install csvkit; Python environments: pip install csvkit). Local and no-egress.