Refactor and enhance DownloadManager application

Refactored and enhanced the DownloadManager application with significant updates across multiple files. Key changes include:

- **App.xaml.cs**: Re-added necessary imports, updated service registrations, and made `OnStartup` asynchronous.
- **DownloadManager.csproj**: Updated target framework, application icon, and added assembly version.
- **DownloadManager.sln**: Updated project format and added configurations for multiple platforms.
- **DownloadManagerService.cs**: Added `HistoryStorageService` dependency, introduced `Initial` method, and improved task management.
- **DownloadWorker.cs**: Enhanced error handling and changed `StartDownloadAsync` to `StartDownload`.
- **ViewModels**: Refactored to use dependency injection, updated task initialization, and added new commands for settings management.
- **UI Updates**: Improved `DownloadingPage.xaml` and `WaitingPage.xaml` with `ListView` and added headers. Restructured `SettingsPage.xaml` for better organization and added new settings options.
- **MainWindow**: Enhanced navigation and applied user-defined themes and backdrops.
- **New Files**: Added `HistoryStorageService.cs`, `ThemeToIndexConverter.cs`, `CompletedItemData.cs`, `Settings.Designer.cs`, `Settings.settings`, `Constants.cs`, `CompletedPageViewModel.cs`, `CompletedPage.xaml`, and `CompletedPage.xaml.cs` to support new features and improvements.

These changes aim to improve the application's robustness, maintainability, and user experience.

Views/Pages/DownloadingPage.xaml

@@ -15,26 +15,39 @@
     ui:Design.Background="{DynamicResource ApplicationBackgroundBrush}"
     ui:Design.Foreground="{DynamicResource TextFillColorPrimaryBrush}"
     Foreground="{DynamicResource TextFillColorPrimaryBrush}"
+    ScrollViewer.CanContentScroll="False"
     mc:Ignorable="d">
 
     <Grid>
-        <ui:VirtualizingItemsControl
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto" />
+            <RowDefinition Height="*" />
+        </Grid.RowDefinitions>
+
+        <Grid Grid.Row="0">
+            <ui:TextBlock
+                Margin="0,0,0,5"
+                HorizontalAlignment="Right"
+                FontTypography="Caption"
+                FontWeight="SemiBold"
+                Text="{Binding ViewModel.DownloadingTask.Count, StringFormat={}{0} Downloading Task}" />
+        </Grid>
+
+        <ui:ListView
+            Grid.Row="1"
+            d:ItemsSource="{d:SampleData ItemCount=2}"
             ItemsSource="{Binding ViewModel.DownloadingTask}"
             ScrollViewer.HorizontalScrollBarVisibility="Disabled"
             VirtualizingPanel.CacheLengthUnit="Item"
             VirtualizingPanel.IsVirtualizing="True"
             VirtualizingPanel.VirtualizationMode="Recycling">
 
-            <ItemsControl.ItemsPanel>
-                <ItemsPanelTemplate>
-                    <StackPanel />
-                </ItemsPanelTemplate>
-            </ItemsControl.ItemsPanel>
-
             <ItemsControl.ItemTemplate>
                 <DataTemplate DataType="{x:Type models:DownloadItemData}">
                     <Border
-                        Height="60"
+                        Height="75"
+                        Padding="10"
+                        Background="{ui:ThemeResource CardBackgroundFillColorDefaultBrush}"
                         CornerRadius="5"
                         ToolTip="{Binding Url}">
                         <Grid>
@@ -86,7 +99,7 @@
 
                                 <Grid Grid.Row="2" Margin="2,0">
                                     <Grid.ColumnDefinitions>
-                                        <ColumnDefinition Width="50" />
+                                        <ColumnDefinition Width="60" />
                                         <ColumnDefinition Width="*" />
                                     </Grid.ColumnDefinitions>
 
@@ -94,7 +107,7 @@
                                         <TextBlock
                                             FontSize="10"
                                             Opacity="0.75"
-                                            Text="{Binding Speed, StringFormat={}{0}MB/s}" />
+                                            Text="{Binding Speed, StringFormat={}{0}MB/s, FallbackValue=0.0}" />
                                     </Grid>
 
                                     <Grid Grid.Column="1">
@@ -136,6 +149,6 @@
                     </Border>
                 </DataTemplate>
             </ItemsControl.ItemTemplate>
-        </ui:VirtualizingItemsControl>
+        </ui:ListView>
     </Grid>
 </Page>