v1.15 — PowerShell edition + repo restructure

- New powershell/InstaSoftOfficeTool.ps1: single-file WPF GUI version
  - Same Fluent Design UI, no compilation needed
  - Runs on any Windows 7+ with PowerShell 5.1 (built-in)
  - Chrome won't flag .ps1 files as "rarely downloaded"
  - Auto-elevates to admin
- Moved C# source to src/ subfolder
- Updated .gitignore for nested bin/obj folders

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

Pages/ConfirmDialog.xaml

@@ -1,41 +0,0 @@
-<UserControl x:Class="InstaSoftOfficeTool.Pages.ConfirmDialog"
-             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
-             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             Visibility="Collapsed">
-
-    <!-- Backdrop overlay -->
-    <Grid>
-        <Border Background="#66000000" MouseDown="Backdrop_MouseDown"/>
-
-        <!-- Dialog card -->
-        <Border Background="{StaticResource CardBrush}" CornerRadius="12"
-                HorizontalAlignment="Center" VerticalAlignment="Center"
-                MinWidth="400" MaxWidth="500" Padding="28,24">
-            <Border.Effect>
-                <DropShadowEffect ShadowDepth="8" BlurRadius="32" Opacity="0.2" Color="Black"/>
-            </Border.Effect>
-
-            <StackPanel>
-                <!-- Icon + Title -->
-                <StackPanel Orientation="Horizontal" Margin="0,0,0,12">
-                    <TextBlock x:Name="DialogIcon" FontFamily="Segoe MDL2 Assets" FontSize="22"
-                               VerticalAlignment="Center" Margin="0,0,12,0"/>
-                    <TextBlock x:Name="DialogTitle" FontSize="18" FontWeight="SemiBold"
-                               VerticalAlignment="Center"/>
-                </StackPanel>
-
-                <!-- Message -->
-                <TextBlock x:Name="DialogMessage" FontSize="14" TextWrapping="Wrap"
-                           Foreground="{StaticResource TextSecondaryBrush}" Margin="0,0,0,24"/>
-
-                <!-- Buttons -->
-                <StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
-                    <Button x:Name="BtnCancel" Style="{StaticResource SecondaryButton}"
-                            Click="BtnCancel_Click" Margin="0,0,8,0"/>
-                    <Button x:Name="BtnConfirm" Style="{StaticResource PrimaryButton}"
-                            Click="BtnConfirm_Click"/>
-                </StackPanel>
-            </StackPanel>
-        </Border>
-    </Grid>
-</UserControl>