Add Portal Settings Web Part with styles, localization, and tests

- Implemented the PortalSettings Web Part with a new manifest and TypeScript file.
- Created SCSS styles for the Web Part, defining various UI elements and responsive design.
- Added localization support for English and German languages.
- Developed tests for Provider Registry and static assets validation.
- Included PowerShell script for project validation.

deployment/Add-PortalSettingsPage.ps1

@@ -0,0 +1,55 @@
+param(
+    [Parameter(Mandatory = $true)]
+    [string]$SiteUrl,
+
+    [string]$PageName = 'PortalSettingsV3',
+
+    [switch]$Publish
+)
+
+$ErrorActionPreference = 'Stop'
+$componentId = 'c41d05ec-0682-4af0-b807-649806ed56b3'
+
+if (-not (Get-Command Connect-PnPOnline -ErrorAction SilentlyContinue)) {
+    throw 'PnP PowerShell wurde nicht gefunden. Bitte das zur SharePoint-SE-Umgebung passende PnP-Modul laden.'
+}
+
+Connect-PnPOnline -Url $SiteUrl -CurrentCredentials
+
+$pageFileName = if ($PageName.EndsWith('.aspx', [StringComparison]::OrdinalIgnoreCase)) { $PageName } else { $PageName + '.aspx' }
+$pageIdentity = $pageFileName.Substring(0, $pageFileName.Length - 5)
+$page = Get-PnPClientSidePage -Identity $pageFileName -ErrorAction SilentlyContinue
+
+if (-not $page) {
+    Write-Host "Erstelle moderne Seite $pageFileName ..." -ForegroundColor Yellow
+    $page = Add-PnPClientSidePage -Name $pageIdentity -LayoutType Article
+}
+else {
+    Write-Host "Verwende vorhandene moderne Seite $pageFileName." -ForegroundColor Yellow
+}
+
+$existingControl = @($page.Controls | Where-Object {
+    $_.WebPartId -and $_.WebPartId.ToString().Equals($componentId, [StringComparison]::OrdinalIgnoreCase)
+}) | Select-Object -First 1
+
+if (-not $existingControl) {
+    if (-not $page.Sections -or $page.Sections.Count -eq 0) {
+        Add-PnPClientSidePageSection -Page $page -SectionTemplate OneColumn -Order 1 | Out-Null
+    }
+    $component = Get-PnPAvailableClientSideComponents -Page $page | Where-Object {
+        $_.Id.ToString().Equals($componentId, [StringComparison]::OrdinalIgnoreCase)
+    } | Select-Object -First 1
+    if (-not $component) {
+        throw 'Das Portal Settings V3 WebPart ist nicht verfügbar. Ist die App im Root Web installiert beziehungsweise aktualisiert?'
+    }
+    Add-PnPClientSideWebPart -Page $page -Component $component -Section 1 -Column 1 -Order 1 | Out-Null
+    Write-Host 'Portal Settings WebPart wurde hinzugefügt.' -ForegroundColor Green
+}
+else {
+    Write-Host 'Portal Settings WebPart ist bereits vorhanden.' -ForegroundColor Green
+}
+
+$page.Save()
+if ($Publish) { $page.Publish() }
+
+Write-Host ("Fertig: " + $SiteUrl.TrimEnd('/') + '/SitePages/' + $pageFileName) -ForegroundColor Green