Need a way to add tags to data-description. For use by automation-capsule when capturing results

**Is your feature request related to a problem? Please describe.**
The metadata-manager can't add `tags` to the derived `data_description.json`. It only carries over tags already present on the source asset — it can't originate one — so pipelines/automation have no way to stamp tags when capturing results.

**Describe the solution you'd like**
Add a `tags` setting (CLI arg) to the metadata-manager that writes to `DataDescription.tags` on the derived output. Perhaps as a list of strs? that append in addition to the default raw/derived and subject_id.

**Describe alternatives you've considered**
- Pre-tagging the raw asset's `data_description.json`. A good solution, but the metadata manager should still have this capability.

**Additional context**
`DataDescription.tags: Optional[List[str]]` already exists and `DerivedDataDescription.from_data_description` already honors it via `get_or_default("tags")`.