* Added Qdrant provider support with factory, config, and protocols
* Improved default embeddings and type definitions
* Fixed ChromaDB factory embedding assignment
### RAG Config System
* Added ChromaDB client creation via config with sensible defaults
* Introduced optional imports and shared RAG config utilities/schema
* Enabled embedding function support with ChromaDB provider integration
* Refactored configs for immutability and stronger type safety
* Removed unused code and expanded test coverage
feat: add RAG system foundation with generic vector store support
- Add BaseClient protocol for vector stores
- Move BaseRAGStorage to rag/core
- Centralize embedding types in embeddings/types.py
- Remove unused storage models
