- Updated V3 CRUD routers to return 400 Bad Request for database schema
errors (unknown columns) across all list and search endpoints.
- Fixed serialization issue in nested patch endpoint.
- Overhauled Section 7 of Frontend Integration Guide to document HTTP
status code mappings for common error categories.
- Updated api_crud_v3 and api_crud_v3_nested to detect 'database_schema'
errors (like Unknown Column) and return a 400 Bad Request instead of
a generic 500 Internal Server Error.
- Added missing error handling for sql_select failure in get_child_obj_li.
- Updated app/db_sql.py to capture SQL exceptions in thread-local storage for later retrieval.
- Implemented format_db_error() in app/lib_api_crud_v3.py to clean up raw MariaDB error strings.
- Added POST /v3/crud/{obj_type}/validate endpoint for dry-run payload validation.
- Updated main and nested routers to bubble up validation and database errors into the response 'meta.details' field.
- Added tests/test_v3_error_bubbling.py to verify formatting logic.
- Created app/routers/api_crud_v3_nested.py to handle all parent-child relational routes.
- Updated app/routers/api_crud_v3.py to include the nested router, significantly reducing file size.
- Documented Phase 2 completion in documentation/REFACTOR_API_CRUD_V3.md.
