Refactor embedding function creation and document loading. Update ingest and query routes to remove unnecessary settings parameters, streamline chunking logic, and enhance load_documents function to handle both string and list inputs. Adjust model name in embedder for consistency with OpenAI API.

Enhance configuration and ingestion functionality for Milestone 4. Update .env.example with new environment variables, expand milestones documentation with integration details, and add necessary dependencies to pyproject.toml and requirements.txt. Refactor ingest and query routes to support file uploads and retrieval, implementing validation and error handling. Update settings to include new model configurations and parameters for chunking and embedding.