Fixed chat conversion of job posting, legal check, and my task assistants (#151)

app/MindWork AI Studio/Assistants/LegalCheck/AssistantLegalCheck.razor.cs

@@ -1,3 +1,5 @@
+using AIStudio.Chat;
+
 namespace AIStudio.Assistants.LegalCheck;
 
 public partial class AssistantLegalCheck : AssistantBaseCore
@@ -30,6 +32,11 @@ public partial class AssistantLegalCheck : AssistantBaseCore
     
     protected override bool SubmitDisabled => this.isAgentRunning;
     
+    protected override ChatThread ConvertToChatThread => (this.chatThread ?? new()) with
+    {
+        SystemPrompt = SystemPrompts.DEFAULT,
+    };
+    
     protected override void ResetFrom()
     {
         this.inputLegalDocument = string.Empty;