Added

• Generalize EmbeddingModel::embed_documents with IntoIterator
• Add from_env constructor to Cohere and Anthropic clients
• Small optimization to serde_json object merging
• Add better error handling for provider clients

Fixed

• Bad Anthropic request/response handling
• (vector-index) In memory vector store index incorrect search

Other

• Made internal json_utils module private
• Update lib docs
• Made CompletionRequest helper method private to crate
• lint + fmt
• Simplify agent_with_tools example
• Fix docstring links
• Add nextest test runner to CI
• Merge pull request #42 from 0xPlaygrounds/refactor(vector-store)/update-vector-store-index-trait