- Added new services: IContentDialogService, ISnackbarService
- Replaced DashboardPage and DashboardViewModel with DownloadingPage, DownloadingPageViewModel, WaitingPage, and WaitingPageViewModel
- Introduced AddNewTaskPage and AddNewTaskViewModel
- Replaced DownloadServiceManger with DownloadManagerService
- Updated WPF-UI package to 3.0.4 and added HtmlAgilityPack 1.11.61
- Refactored DownloadWorker to use async methods and added retry logic
- Converted DownloadItemData to partial class with ObservableProperty attributes
- Changed initial navigation page to DownloadingPage
- Updated MainWindow navigation items and title
- Added new utility classes: DoubleUtilities, MD5Utilities, StringExtension
- Added new XAML pages and ViewModels for task management and display
- Removed obsolete DashboardPage and related files
