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

Scripts/FileIO/Save-Settings.ps1

@@ -0,0 +1,31 @@
+<#
+    .SYNOPSIS
+        Saves active feature settings, excluding control parameters, unless running in WhatIf mode.
+#>
+function Save-Settings {
+    if ($script:Params.ContainsKey("WhatIf")) {
+        Write-Host "[WhatIf] Save settings to LastUsedSettings.json" -ForegroundColor Cyan
+        return
+    }
+
+    $settings = @{
+        "Version" = "1.0"
+        "Settings" = @()
+    }
+    
+    foreach ($param in $script:Params.Keys) {
+        if ($script:ControlParams -notcontains $param -and $script:Features.ContainsKey($param)) {
+            $value = $script:Params[$param]
+
+            $settings.Settings += @{
+                "Name" = $param
+                "Value" = $value
+            }
+        }
+    }
+
+    if (-not (Save-ToFile -Config $settings -FilePath $script:SavedSettingsFilePath)) {
+        Write-Output ""
+        Write-Host "Error: Failed to save settings to LastUsedSettings.json file" -ForegroundColor Red
+    }
+}