Improve devcontainer setup script with better error handling and fallback

Co-authored-by: BenjaminMichaelis <22186029+BenjaminMichaelis@users.noreply.github.com>

Author: Copilot

.devcontainer/setup.sh

@@ -22,6 +22,9 @@ if [ -z "$NUGET_AUTH_TOKEN" ]; then
 else
     echo "✅ Azure DevOps PAT token found - configuring private NuGet feed..."
 
+    # Remove existing source if it exists, then add with authentication
+    dotnet nuget remove source "EssentialCSharp" --configfile nuget.config 2>/dev/null || true
+    
     # Configure Azure DevOps NuGet source with authentication
     dotnet nuget add source "https://pkgs.dev.azure.com/intelliTect/_packaging/EssentialCSharp/nuget/v3/index.json" \
         --name "EssentialCSharp" \
@@ -31,7 +34,14 @@ else
         --configfile nuget.config
 
     echo "🔧 Restoring packages with private feed access..."
-    dotnet restore -p:AccessToNugetFeed=true
+    if dotnet restore -p:AccessToNugetFeed=true; then
+        echo "✅ Package restore successful with private feed access!"
+    else
+        echo "⚠️  Package restore failed with private feed access."
+        echo "   This might indicate an authentication issue with the Azure DevOps PAT token."
+        echo "   Falling back to public packages only..."
+        dotnet restore -p:AccessToNugetFeed=false
+    fi
 fi
 
 echo "✅ Setup complete!"

nuget.config

@@ -14,4 +14,10 @@
             <package pattern="ContentFeedNuget" />
         </packageSource>
     </packageSourceMapping>
+  <packageSourceCredentials>
+    <EssentialCSharp>
+        <add key="Username" value="devcontainer" />
+        <add key="ClearTextPassword" value="test-token" />
+      </EssentialCSharp>
+  </packageSourceCredentials>
 </configuration>