Let the Assistant Builder generate launchers without a workspace

app/MindWork AI Studio/Assistants/Builder/AssistantBuilderChatLaunchMetadata.cs

@@ -2,6 +2,10 @@ namespace AIStudio.Assistants.Builder;
 
 internal sealed class AssistantBuilderChatLaunchMetadata
 {
+    /// <summary>
+    /// The workspace the chat is created in. A model leaves this field out for a launcher that
+    /// opens a chat without a workspace, which is why it stays empty rather than null.
+    /// </summary>
     public string WorkspaceName { get; init; } = string.Empty;
     public string? ProviderId { get; init; }
     public string? ProfileId { get; init; }