V3 deterministic CSV statistics capability pack. By-value connector composition (service_kind=cli, no separate ingredient): the local csvstat CLI summarizes one trusted local CSV path as JSON via the csv.stats catalog operation. This is the reproducible csvkit-backed fallback for qsv stats while qsv lacks a Debian-stable package. Path-based by design: stats are stdout value output, so this operation does not combine file_ref materialization with stdout capture. Requires csvkit on PATH (Debian/Ubuntu: apt install csvkit; Python environments: pip install csvkit). Local and no-egress.