fix: remove unused imports in test_langgraph.py (ruff F401)

feat: add LangGraph compress_tool_messages node for ToolMessage compression

Fix LangChain tool_call argument handling for varied message formats

fix: improve error handling and add comprehensive test coverage

Add reasoning capability forwarding to HeadroomAgnoModel

Add Phase 2 Progressive Summarization and fix Agno integration tests

Fix test_on_llm_error to pass required run_id argument

Fix HeadroomAgnoModel to extend agno.models.base.Model and add real integration tests

Add Agno agent framework integration

Add seamless LangChain integration

Fix all ruff lint and format errors for CI

Initial commit: Headroom SDK - LLM context optimization toolkit