Improve documentation and error handling in VectorStore embeddings module

[Adityanagraj]

The src/core/embeddings.py module provides vector embeddings and database functionality using LangChain and Chroma. While the code has basic logging and exception handling, the following areas could be improved:

1. Documentation:

   • Docstrings for methods, especially for parameters and return values.
   • Usage examples for the VectorStore class.
   • Clarify expected input types, e.g., documents: List.

2. Error Handling:

   • Add more informative error messages.
   • Consider custom exception classes for database operations.

3. Type Annotations:

   • Specify types for documents parameter (e.g., List[Document]) if possible.

4. Testing:

   • Unit tests for create_vector_db and delete_collection methods.
   • Test for edge cases (empty documents, invalid model name, etc.).

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Please provide the following details to help refine this issue:

• Are there specific use cases or bugs you've encountered?
• Should the issue target documentation, code improvements, or both?
• Any preferred format or style for docstrings and error messages?
• Do you have examples of typical documents input?
• Should this include writing new tests, or just improvements to current code?