Summary

• Add comprehensive type annotations to all 11 abstract methods in VectorStoreBase
• Add detailed parameter and return type docstrings following Google style
• Add missing default value for memory_action parameter in EmbeddingBase.embed()
• Fix typo in reset() docstring ("delete" -> "deleting")

Motivation

The VectorStoreBase abstract class had no type hints on any of its method signatures, while concrete implementations (e.g., Qdrant, Chroma) already use typed parameters. This creates a gap where:

• IDEs cannot provide autocompletion when coding against the base class
• Static type checkers (mypy, pyright) cannot verify implementations match the contract
• New contributors implementing custom vector stores have to read concrete implementations to understand expected types

Changes

mem0/vector_stores/base.py:

• Added typing imports (Any, Dict, List, Optional, Union)
• Annotated all parameters and return types across 11 abstract methods
• Added Google-style docstrings with Args/Returns sections

mem0/embeddings/base.py:

• Added return type -> list to embed() method
• Added default = None for memory_action parameter (matching all implementations)
• Cleaned up docstring formatting

Test plan

• Verify existing tests pass (no behavioral changes, only annotations)
• Confirm type annotations match concrete implementations (Qdrant, Chroma, Pinecone, etc.)