- Add filter, index_type, included_columns, and comment fields to IndexInfo
- PostgreSQL: query pg_am for index type, use indnkeyatts to split key/included columns, retrieve index comments via obj_description()
- SQL Server: add type_desc, filter_definition, included columns via is_included_column
- MySQL: add INDEX_TYPE from information_schema.STATISTICS
- Oracle: add INDEX_TYPE from ALL_INDEXES
- DDL generation: add USING (PostgreSQL), type prefix + INCLUDE + WHERE (SQL Server), COMMENT ON INDEX (PostgreSQL)
- Frontend: update types, state mapping, SQL generation, and i18n translations