CI: conditionally restore Windows TFM; build AppHost only on Windows runners to avoid missing Windows runtime packs on non-Windows CI/tooling

.github/workflows/build.yml

@@ -22,16 +22,25 @@ jobs:
       - name: Install MAUI workload
         run: dotnet workload install maui
 
-      - name: Restore
+      - name: Restore (Windows)
-        # Skip restoring the Windows target frameworks to avoid requiring Windows runtime packs in CI/tooling environments
+        if: runner.os == 'Windows'
+        run: dotnet restore SlipItIn.slnx
+
+      - name: Restore (non-Windows)
+        if: runner.os != 'Windows'
+        # Skip restoring the Windows target frameworks to avoid requiring Windows runtime packs in non-Windows CI/tooling environments
         run: dotnet restore SlipItIn.slnx -p:SkipWindowsTargetFramework=true
 
-      - name: Build Server-Stack
+      - name: Build Server-Stack (core projects)
         run: |
           dotnet build SlipItIn.Shared/SlipItIn.Shared.csproj --no-restore --configuration Release
           dotnet build SlipItIn.ServiceDefaults/SlipItIn.ServiceDefaults.csproj --no-restore --configuration Release
           dotnet build SlipItIn.Server/SlipItIn.Server.csproj --no-restore --configuration Release
           dotnet build SlipItIn.Server.Tests/SlipItIn.Server.Tests.csproj --no-restore --configuration Release
+
+      - name: Build AppHost
+        if: runner.os == 'Windows'
+        run: |
           dotnet build SlipItIn.AppHost/SlipItIn.AppHost.csproj --no-restore --configuration Release
 
       - name: Build MAUI Client