- Add UserAgentCatalogSeed and UserAgentCatalogYaml Pydantic models
- Add load_user_agent_catalog function to load from YAML
- Add _upsert_user_agent_catalog helper for upsert logic
- Add initialize_user_agent_catalog function for initialization
- Refactor initialize_data to call initialize_llm_catalog and initialize_user_agent_catalog
- Fix UserAgentCatalog.llm_id type from str to uuid.UUID
replace monolithic migration with ordered scripts, include profiles/sessions in migration, and verify full downgrade/upgrade cycle for clean Supabase bootstrap