Add autopep8 as a dependency for code formatting - Updated pyproject.toml to include autopep8 version 2.3.2 for improved code style consistency. Modified uv.lock to reflect the new dependency and its requirements. This update aims to enhance code maintainability and adherence to style guidelines.

Enhance intent-aware recommendation system design and scoring logic - Updated the design document to introduce a new query type for "by artist" intent, detailing user goals, scoring strategies, and agent workflows. Refactored scoring logic in the quality scorer and ranking logic to accommodate exploration preferences and artist alias handling. Improved candidate generation for artist-specific queries and refined genre filtering methods to support hybrid queries. This update aims to better align system behavior with user intent and enhance overall recommendation accuracy.

Update .gitignore and remove obsolete cleanup documentation - Added `.gradio` and `tests/data/cache` to `.gitignore` to prevent unnecessary file tracking. Deleted outdated cleanup documentation files (`AGENT_CLEANUP_COMPLETION.md` and `CLEANUP_PLAN.md`) to streamline the codebase and remove obsolete references. This cleanup supports ongoing refactoring efforts and enhances overall project maintainability.