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; }

app/MindWork AI Studio/Assistants/Builder/AssistantBuilderLuaResponse.schema.json

@@ -131,11 +131,9 @@
     "chatLaunch": {
       "type": "object",
       "additionalProperties": false,
-      "required": [
-        "workspace_name"
-      ],
       "properties": {
         "workspace_name": {
+          "description": "Omit this field for a launcher that opens a chat without a workspace.",
           "type": "string",
           "minLength": 1
         },

app/MindWork AI Studio/Assistants/Builder/LuaResponse.Parse.cs

@@ -124,7 +124,12 @@ internal sealed partial class LuaResponse
 
     private static bool IsValidChatLaunchMetadata(AssistantBuilderChatLaunchMetadata? launch)
     {
-        if (launch is null || string.IsNullOrWhiteSpace(launch.WorkspaceName))
+        //
+        // A missing workspace name describes a launcher that opens a chat without a workspace, so
+        // only the launch block itself is mandatory here. Whether the name matches the plugin the
+        // model wrote is decided later, by comparing both.
+        //
+        if (launch is null)
             return false;
 
         if (!IsOptionalGuid(launch.ProviderId, allowEmpty: false) ||