- extract_sql(): deterministic tree-sitter extraction of tables, views,
functions, foreign key references, and FROM/JOIN reads_from edges
- .sql added to CODE_EXTENSIONS and dispatch table
- tree-sitter-sql added as optional dep under [sql] extra
- xlsx_extract_structure(): extracts sheet/table/column nodes from .xlsx
(utility — pipeline wiring in follow-up)
- 6 new SQL tests, 447 total passing
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>