Vector-store compatibility fix
- Restores existing ChromaDB 1.x collections after upgrading to the pinned safe 0.6 runtime.
- Migrates only the known empty legacy configuration and creates a database backup first.
- Preserves existing embeddings, so no document reprocessing or re-embedding is required.
- Surfaces unexpected storage failures instead of silently reporting an empty knowledge base.
Validated on Windows and Linux, with 566 Python tests and 40 Node tests passing.
Full Changelog: v2.2.1...v2.2.2