Sync model catalog

Keeps the agent model catalog honest. The catalog is the curated decoration over each harness's accepted model set: clean labels, one-sentence descriptions, real pricing, and 1-5 ratings, keyed by the id the harness accepts. It is published additively next to the ids-only models map on the harness capability record (capabilities.py).

Design and rationale: docs/design/agent-workflows/projects/model-catalog-schema/{design.md,plan.md}.

What it owns

Three JSON data files under sdks/python/agenta/sdk/agents/data/, loaded by sdks/python/agenta/sdk/agents/model_catalog.py: