* Add DotProduct Method and README Example for Embedding Similarity Search
- Implement a DotProduct() method for the Embedding struct to calculate the dot product between two embeddings.
- Add a custom error type for vector length mismatch.
- Update README.md with a complete example demonstrating how to perform an embedding similarity search for user queries.
- Add unit tests to validate the new DotProduct() method and error handling.
* Update README to focus on Embedding Semantic Similarity
