[Domain] Move model_cards.domain FK to model_cards.domain_id

Goal

Move the foreign key reference from ``model_cards.domain`` (string, → ``domains.name``) to a new ``model_cards.domain_id`` (UUID, → ``domains.id``). The legacy ``domain`` string column is retained without a FK constraint; removal is deferred to BA-6122. ``domains`` keeps ``name`` as PK in this story — the PK swap is BA-6046.

Scope

1. Alembic: single revision, parent ``down_revision = fdc9d6ac49b4``. Add ``model_cards.domain_id`` UUID column (NOT NULL). Backfill via join on ``domains.name``. Drop legacy ``domain → domains.name`` FK (``ON DELETE RESTRICT``); create new ``domain_id → domains.id`` FK with the same ``RESTRICT`` semantics. Downgrade reverses.

2. ORM: add ``domain_id: Mapped[DomainID]`` on ``ModelCardRow``; keep ``domain`` column (drop only its FK clause).

3. Create / update specs: add ``domain_id: DomainID`` to ``ModelCardCreatorSpec`` in ``repositories/model_card/creators.py``. ``build_row`` populates both columns.

4. API entry point: ``api/adapters/model_card/adapter.py::create`` resolves ``domain_id`` via ``ResolveDomainIDByNameAction`` before constructing the spec.

5. Tests: update fixtures that construct ``ModelCardRow`` directly so ``domain_id`` is populated.

Parallelism

Independent of the other 9 referencing-table stories. Alembic head consolidation happens under BA-6046.

Out of scope

- ``domains`` PK swap — BA-6046.

- Legacy column drop — BA-6122.

JIRA Issue: BA-6130

Start with the Alembic revision whose parent is fdc9d6ac49b4, then inspect ModelCardRow, repositories/model_card/creators.py, and api/adapters/model_card/adapter.py. Update the direct ModelCardRow fixtures named in the issue and run the affected tests. Done means the migration backfills domain_id, preserves the legacy column without its FK, reverses cleanly on downgrade, and the ORM, creator, adapter, and tests agree.

Written by the indexing model from the issue text.