Add comprehensive test suite, fix minor issues, rename function and file names to match approved verbs (#708)

Scripts/GUI/Show-AboutDialog.ps1

@@ -1,3 +1,10 @@
+<#
+    .SYNOPSIS
+        Displays the themed About dialog for the application.
+
+    .PARAMETER Owner
+        The optional window that owns the dialog and its modal overlay.
+#>
 function Show-AboutDialog {
     param (
         [Parameter(Mandatory=$false)]
@@ -6,7 +13,7 @@ function Show-AboutDialog {
     
     Add-Type -AssemblyName PresentationFramework,PresentationCore,WindowsBase | Out-Null
     
-    $usesDarkMode = GetSystemUsesDarkMode
+    $usesDarkMode = Get-SystemUsesDarkMode
     
     # Determine owner window
     $ownerWindow = if ($Owner) { $Owner } else { $script:GuiWindow }
@@ -42,7 +49,7 @@ function Show-AboutDialog {
     }
 
     # Apply theme resources
-    SetWindowThemeResources -window $aboutWindow -usesDarkMode $usesDarkMode
+    Set-WindowThemeResources -window $aboutWindow -usesDarkMode $usesDarkMode
     
     # Get UI elements
     $titleBar = $aboutWindow.FindName('TitleBar')
@@ -95,4 +102,4 @@ function Show-AboutDialog {
             catch { }
         }
     }
-}
+}