ci(welcome): build + test the Welcome solution before the ISO build

.gitea/workflows/build-iso-windows.yaml

@@ -58,6 +58,27 @@ jobs:
           }
           if (-not (Test-Path $deploy)) { throw 'ADK Deployment Tools install failed.' }
 
+      - name: Ensure .NET 9 SDK + MAUI workload
+        shell: pwsh
+        run: |
+          # Ensure dotnet 9 is available (setup-dotnet may have cached it; self-hosted
+          # runners should already have it, but this makes the step idempotent).
+          $dotnet = Get-Command dotnet -EA SilentlyContinue
+          if ($dotnet) {
+            $ver = (dotnet --version 2>$null) -replace '\+.*',''
+            Write-Host "dotnet found: $ver"
+          } else {
+            throw 'dotnet not found on runner. Add actions/setup-dotnet@v4 to this job.'
+          }
+          Write-Host 'Installing/repairing MAUI workload (idempotent)...'
+          dotnet workload install maui
+          Write-Host 'MAUI workload ready.'
+
+      - name: Build + test SilverOS Welcome
+        shell: pwsh
+        run: |
+          dotnet test windows/welcome/SilverOS.Welcome.sln -c Release
+
       - name: Acquire base ISO
         id: iso
         shell: pwsh