Emit database column comments as JSDoc in generated types #91

What to build

Surface database column comments in the generated output as /** … */ JSDoc leading comments on the generated declarations, so they show up as editor type hints.

The introspection half is already done: the shared column-metadata already carries a comment field, populated today for MySQL and MariaDB (information_schema.COLUMNS.COLUMN_COMMENT), Postgres (pg_description), and MSSQL (sys.extended_properties / MS_Description). The comment is currently only forwarded to Sequelize's runtime comment option, not rendered as a code-level doc comment. No introspection query changes are required.

The work is purely in the emitter: attach a synthetic leading JSDoc comment (ts.addSyntheticLeadingComment with MultiLineCommentTrivia, text lead * to produce /** … */) to the generated declarations, in both output formats:

• Native format: on the declare attribute property declarations (the primary v13 format).
• Decorator format: on the class property (above its @Column decorator) and the strict Attributes interface property signature — the block PR Add comment generation to TypeScript interfaces #61 originally patched.

Acceptance criteria

• Columns with a non-empty comment render a /** <comment> */ JSDoc leading comment on the generated declaration in the native format (declare attributes) and the decorator format (class property and Attributes interface).
• Empty/whitespace comments produce no comment (MySQL/MariaDB return '' rather than null — guard on truthiness).
• SQLite is a no-op (PRAGMA exposes no column comments) and is unaffected.
• Comment text is sanitised so an embedded */ cannot prematurely close the JSDoc block.
• Integration tests: for MySQL, MariaDB, Postgres, and MSSQL a column carrying a comment produces the JSDoc in generated output; SQLite output is unchanged. Reuse PR Add comment generation to TypeScript interfaces #61's per-dialect comment-seeding SQL (MySQL/MariaDB COMMENT '…', Postgres COMMENT ON COLUMN …, MSSQL sp_addextendedproperty … 'MS_Description').
• On completion (once this change is merged), close PR Add comment generation to TypeScript interfaces #61 with a comment pointing to this ticket.

Blocked by

None (can start immediately).

Source

Extracted from PR #61 (predates the v13 native emitter; only patched the decorator Attributes interface). Reuse its addSyntheticLeadingComment approach and test seed SQL; redo placement to also cover the native emitter. Supersedes PR #61 — close it pointing here.