Moved the chats of the BeyondFacts Lab to the embedded chat of assistants (#1203)

app/MindWork AI Studio/Chat/Embedded/EmbeddedChatRequest.cs

@@ -27,13 +27,8 @@ public sealed record EmbeddedChatRequest
 
     /// <summary>
     /// Readies the chat for the request before the message goes in: its system prompt, profile, tools, and data
-    /// sources, which a chat partly does not store. Returns false to send nothing; it tells the user why itself.
+    /// sources, which a chat partly does not store. Returns what the request carries beside the stored chat, or
+    /// EmbeddedChatPreparation.REFUSED to send nothing; it tells the user why itself.
     /// </summary>
-    public Func<ChatThread, Task<bool>> PrepareAsync { get; init; } = _ => Task.FromResult(true);
-
-    /// <summary>
-    /// Gets the chat which the request sends, e.g., with images which the stored chat never holds. The chat itself
-    /// by default.
-    /// </summary>
-    public Func<ChatThread, ChatThread> ThreadForRequest { get; init; } = thread => thread;
+    public Func<ChatThread, Task<EmbeddedChatPreparation>> PrepareAsync { get; init; } = _ => Task.FromResult(EmbeddedChatPreparation.READY);
 }