- Updated DatasetInfo schema to include columns and metrics fields, with new TableColumnInfo and SqlMetricInfo models.
- Updated serialize_dataset_object to serialize columns and metrics for each dataset.
- Modified list_datasets tool to use serialize_dataset_object and include columns/metrics by default.
- Improved and fixed all related unit tests to use proper MagicMock objects for columns/metrics and to parse JSON responses.
- Ensured LLM/OpenAPI compatibility for dataset listing and info tools.
