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/EditionPage.xaml

@@ -0,0 +1,20 @@
+<Page x:Class="InstaSoftOfficeTool.Pages.EditionPage"
+      xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
+      xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+      Background="Transparent">
+
+    <Grid Margin="40,30">
+        <Grid.RowDefinitions>
+            <RowDefinition Height="Auto"/>
+            <RowDefinition Height="*"/>
+        </Grid.RowDefinitions>
+
+        <StackPanel Grid.Row="0" Margin="0,0,0,24">
+            <TextBlock x:Name="TitleText" Text="Valasszon kiadast" FontSize="24" FontWeight="Light"/>
+            <TextBlock x:Name="SubtitleText" FontSize="14"
+                       Foreground="{StaticResource TextSecondaryBrush}" Margin="0,4,0,0"/>
+        </StackPanel>
+
+        <StackPanel x:Name="EditionPanel" Grid.Row="1" VerticalAlignment="Top"/>
+    </Grid>
+</Page>