feat(download):Add tabbed download manager with active and completed task tracking

- Implement DownloadTask class with status tracking and progress monitoring
- Add TabController to separate active downloads from completed files
- Create periodic refresh for real-time active task status updates
- Add download cancellation functionality with confirmation dialogs
- Implement task record management with delete options
- Enhance UI with status colors, progress bars, and detailed task information
- Add background download support with progress tracking
- Integrate completed task history with file system listings

Author: Suyunmeng