Add src/dsl/sql_functions.rs (KNOWN_SQL_FUNCTIONS) as the shared source
of truth at sql_expr_ident slots:
- #15: offer the functions as Tab candidates under a new
CandidateKind::Function + ninth Theme colour tok_function (blue,
distinct from keyword/identifier/type).
- #16: restore the column-typo flag the #6 fix had dropped wholesale —
invalid_ident_at_cursor now bails only when the partial prefix-matches
a known function, else falls through to the schema-column check.
A column named like a function (e.g. `count`) is deduped (column wins).
`cast` is excluded — CAST(x AS type) is not a plain-call shape.
The no-validation-allowlist posture stands: the list drives completion +
the typo hint only, never parse-time acceptance.
Docs: ADR-0022 Amendment 6, ADR-0031 status note, README index,
requirements I3/I4 + refreshed test baseline.
claude@clouddev1
6d8c9eea36