- Bump langgraph from 0.4 to 1.0+, langgraph-supervisor from 0.0.12 to 0.0.30+
- Bump langchain-core, langchain-anthropic, langchain-openai to 1.x
- Add langchain>=1.0 dependency for new create_agent location
- Migrate create_react_agent -> create_agent (prompt -> system_prompt)
- Fix create_supervisor positional arg to named agents= parameter
- Replace AsyncMock checkpointer with InMemorySaver in tests (v1 type validation)
- Update version references in README, ARCHITECTURE, eng-review-plan
