v1.16 — Remove PowerShell edition, restore flat project structure

PowerShell version removed — will use OV code signing certificate instead.
Files moved back from src/ to project root.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Pages/VersionPage.xaml.cs

@@ -0,0 +1,34 @@
+using System.Windows.Controls;
+using InstaSoftOfficeTool.Models;
+
+namespace InstaSoftOfficeTool.Pages
+{
+    public partial class VersionPage : Page, IWizardPage
+    {
+        private readonly MainWindow _main;
+        private readonly InstallConfig _config;
+
+        public VersionPage(MainWindow main, InstallConfig config)
+        {
+            InitializeComponent();
+            _main = main;
+            _config = config;
+
+            // Restore selection
+            switch (_config.Version)
+            {
+                case OfficeVersion.Office2024: Rb2024.IsChecked = true; break;
+                case OfficeVersion.Office2021: Rb2021.IsChecked = true; break;
+                case OfficeVersion.Office2019: Rb2019.IsChecked = true; break;
+            }
+        }
+
+        public bool Validate()
+        {
+            if (Rb2024.IsChecked == true) _config.Version = OfficeVersion.Office2024;
+            else if (Rb2021.IsChecked == true) _config.Version = OfficeVersion.Office2021;
+            else if (Rb2019.IsChecked == true) _config.Version = OfficeVersion.Office2019;
+            return true;
+        }
+    }
+}