Write, validate, and (optionally) execute an NQL query against a
Narrative dataset. Drafts the query from the user's question, runs
`narrative_nql_validate` until it compiles, explains the query in
plain English, and only runs it on explicit approval (or when
invoked with `--run`).
Use when: "write an NQL query for X", "query this dataset",
"validate this NQL", "run NQL against dataset <id>", "how many rows
match Y", "show me the top N records from <dataset>".
(narrative-common)
