Fix ruff lint errors in test files

feat: add live traffic learning + cross-agent memory writers (--learn flag)

feat(router): adaptive compression with Read lifecycle and context-pressure scaling

Fix CI: guard starlette imports, asyncio.run(), deprecate datetime.utcnow()

Add centralized ML model configuration

Fix test to expect VectorBackend.AUTO as default

Add multi-provider memory system with auto-detection

fix(tests): skip memory tests when hnswlib not available

Add DiffCompressor and fix hnswlib SIGILL crash on CI

Fix asyncio event loop error in Python 3.10+ tests

Add global httpx.ReadTimeout handler for memory tests

Fix mypy errors and add network timeout handler for flaky CI tests

Add hierarchical memory system with graph + vector storage

Make hnswlib optional and skip tests when unavailable

Replace legacy memory system with HierarchicalMemory

Add persistent memory system with zero-latency inline extraction