- Add migration script (scripts/migrate_jsonb.py) that converts
89,443 Python dict repr rows to valid JSON via ast.literal_eval
- Column altered from TEXT to native JSONB
- Index created on generation_metadata->>'merge_group_hint'
- Remove unnecessary ::jsonb casts in pipeline_adapter.py
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>