Walk a Data Analyst through a SQL file against its review artifacts as an interactive, in-session explanation — no new file is produced. Use when someone needs SQL explained against its review doc(s) and JSON, wants to see how the code maps to the documented assumptions and limitations, or is picking up a prior review and asks "what changed?". Triggers on requests to explain, walk through, or talk through SQL alongside its `.sqlreview/` artifacts, even if the folder isn't named. Resumes a previous explanation via git diff and double-checks unchanged code for indirect consequences. Final step of the SQL Review suite (after setup, bootstrap, analyse).
