minor bug fixes and overall ui improvements

[arabcoders]

This pull request introduces the download_skipped flag to track when downloads are intentionally skipped (e.g., via --skip-download or --simulate) throughout the backend, persistence layer, and frontend UI. It ensures that the flag is set and propagated in download status updates, persisted in storage, and reflected in the UI to prevent retry actions and display appropriate icons and status messages. The changes also include improved handling of playlist metadata and comprehensive tests to verify the new behavior.

Backend: Download Flow and Status Tracking

• Added a download_skipped boolean to ItemDTO and updated the download logic in core.py to detect when downloads are skipped based on yt-dlp options. This flag is now included in all status queue updates, ensuring accurate tracking and propagation.
• Improved logic for merging playlist metadata, preferring real playlist values over placeholders when updating info dictionaries.

Frontend: UI/UX Updates

• Updated the History.vue component to use the download_skipped flag for determining retry action visibility, status icon, icon color, and status message, providing clear feedback when downloads are intentionally skipped. [1] [2] [3] [4] [5] [6] [7]