feat: implement robust YouTube transcript downloader with multi-provider fallback strategy and modular API routing

feat: implement Pydantic configuration management, add end-to-end pipeline testing, and include documentation for the recommendation module.

Mt5

chore: update project dependencies in pyproject.toml

feat: implement asynchronous YouTube note generation pipeline and API endpoints

fix: update summarization schema and assemblyai fallback

v2.1

server v2