Warn before software closed; fix bug on first run

Also put settings into proper dir

src/Views/MainView.axaml

@@ -223,7 +223,7 @@
         <StackPanel Orientation="Horizontal"
                     Spacing="4">
             <Button Command="{Binding AddItem}"
-                    IsEnabled="{Binding !IsCreatingPDF}">
+                    IsEnabled="{Binding CanAddItem}">
                 <TextBlock><Run Text="&#x002b;" FontFamily="{StaticResource FontAwesomeSolid}"/> Add Item(s)</TextBlock>
             </Button>
             <Button Command="{Binding SaveInterimReportInfo}"

src/Views/MainView.axaml.cs

@@ -3,6 +3,7 @@ using Avalonia;
 using Avalonia.Controls;
 using Avalonia.Input;
 using Avalonia.Markup.Xaml;
+using MayShow.ViewModels;
 
 namespace MayShow.Views
 {
@@ -12,6 +13,7 @@ namespace MayShow.Views
         {
             this.InitializeComponent();
             LogBlock.PropertyChanged += LogBlock_PropertyChanged;
+            FilesGrid.CellEditEnded += FileCellEditEnded;
         }
 
         private void LogBlock_PropertyChanged(object? sender, AvaloniaPropertyChangedEventArgs e)
@@ -26,6 +28,18 @@ namespace MayShow.Views
         {
             var topLevel = TopLevel.GetTopLevel(this);
             topLevel?.FocusManager?.ClearFocus();
+            if (DataContext is MainViewModel mvm)
+            {
+                mvm?.HasUnsavedWork = true;
+            }
+        }
+
+        private void FileCellEditEnded(object? sender, DataGridCellEditEndedEventArgs args)
+        {
+            if (args.EditAction == DataGridEditAction.Commit && DataContext is MainViewModel mvm)
+            {
+                mvm?.HasUnsavedWork = true;
+            }
         }
     }
 }

src/Views/ShutdownCheckView.axaml

@@ -0,0 +1,39 @@
+<UserControl xmlns="https://github.com/avaloniaui"
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
+             x:Class="MayShow.Views.ShutdownCheckView"
+             xmlns:models="clr-namespace:MayShow.Models"
+             xmlns:vm="clr-namespace:MayShow.ViewModels"
+             xmlns:dialogHost="clr-namespace:DialogHostAvalonia;assembly=DialogHost.Avalonia"
+             x:DataType="vm:ShutdownCheckViewModel">
+    <StackPanel Orientation="Vertical"
+                Spacing="4">
+        <TextBlock TextAlignment="Center"
+                   FontWeight="Bold"
+                   FontSize="18"
+                   Text="Warning: You have unsaved report data!"/>
+        <TextBlock TextAlignment="Center"
+                   FontWeight="Bold"
+                   TextWrapping="Wrap"
+                   FontSize="14"
+                   Text="Do you want to save your data before the program is closed?"/>
+        <StackPanel Orientation="Horizontal"
+                    Spacing="8">
+            <Button Command="{Binding SaveAndShutdown}"
+                    Classes="accent"
+                    Content="Save Data and Close"
+                    HorizontalAlignment="Right"
+                    Margin="0,4,0,4"/>
+            <Button Command="{Binding DoNotSaveAndShutdown}"
+                    Content="Do NOT Save Data and Close"
+                    HorizontalAlignment="Right"
+                    Margin="0,4,0,4"/>
+            <Button Command="{Binding CancelShutdown}"
+                    Content="Cancel Program Shutdown"
+                    HorizontalAlignment="Right"
+                    Margin="0,4,0,4"/>
+        </StackPanel>
+    </StackPanel>
+</UserControl>

src/Views/ShutdownCheckView.axaml.cs

@@ -0,0 +1,14 @@
+using System;
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Markup.Xaml;
+
+namespace MayShow.Views;
+
+public partial class ShutdownCheckView : UserControl
+{
+    public ShutdownCheckView()
+    {
+        this.InitializeComponent();
+    }
+}