Add solution and project files; introduce .gitignore and clean IDE/build artifacts

MainWindow.xaml.cs

@@ -0,0 +1,72 @@
+using System;
+using System.IO;
+using System.Net.Http;
+using System.Threading.Tasks;
+using System.Windows;
+using Ookii.Dialogs.Wpf;     // ← add this
+
+namespace MossyUpdater
+{
+    public partial class MainWindow : Window
+    {
+        public MainWindow()
+        {
+            InitializeComponent();
+        }
+
+        private void Browse_Click(object sender, RoutedEventArgs e)
+        {
+            var dlg = new VistaFolderBrowserDialog
+            {
+                Description = "Select a destination folder",
+                UseDescriptionForTitle = true
+            };
+
+            // ShowDialog returns true if the user clicked OK
+            if (dlg.ShowDialog() == true)
+                FolderTextBox.Text = dlg.SelectedPath;
+        }
+
+        private async void Download_Click(object sender, RoutedEventArgs e)
+        {
+            string url = UrlTextBox.Text.Trim();
+            string folder = FolderTextBox.Text.Trim();
+            string filename = FilenameTextBox.Text.Trim();
+
+            if (string.IsNullOrEmpty(url)
+             || string.IsNullOrEmpty(folder)
+             || string.IsNullOrEmpty(filename))
+            {
+                StatusTextBlock.Text = "Please fill in all fields.";
+                StatusTextBlock.Foreground = System.Windows.Media.Brushes.Red;
+                return;
+            }
+
+            string fullPath = Path.Combine(folder, filename);
+
+            try
+            {
+                using var client = new HttpClient();
+                var data = await client.GetByteArrayAsync(url);
+                await File.WriteAllBytesAsync(fullPath, data);
+
+                UnblockFile(fullPath);
+
+                StatusTextBlock.Text = $"Downloaded and unblocked:\n{fullPath}";
+                StatusTextBlock.Foreground = System.Windows.Media.Brushes.Green;
+            }
+            catch (Exception ex)
+            {
+                StatusTextBlock.Text = $"Error: {ex.Message}";
+                StatusTextBlock.Foreground = System.Windows.Media.Brushes.Red;
+            }
+        }
+
+        private void UnblockFile(string path)
+        {
+            var zone = path + ":Zone.Identifier";
+            if (File.Exists(zone))
+                File.Delete(zone);
+        }
+    }
+}