Added the Model Comparison assistant for blind comparisons of two models (#1009)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

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

@@ -0,0 +1,39 @@
+namespace AIStudio.Chat.Embedded;
+
+/// <summary>
+/// A message for an embedded chat, together with what the assistant decides about the request it starts.
+/// </summary>
+public sealed record EmbeddedChatRequest
+{
+    /// <summary>
+    /// The provider which answers.
+    /// </summary>
+    public required AIStudio.Settings.Provider Provider { get; init; }
+
+    /// <summary>
+    /// The message, with its attachments. The chat stores it as it is.
+    /// </summary>
+    public required ContentText Message { get; init; }
+
+    /// <summary>
+    /// Whether the user does not see the message, e.g., a request which lets the model open a conversation.
+    /// </summary>
+    public bool IsHidden { get; init; }
+
+    /// <summary>
+    /// Whether messages to the user leave out which provider and which model answer, see IProvider.HidesIdentity.
+    /// </summary>
+    public bool HidesModelIdentity { get; init; }
+
+    /// <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.
+    /// </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;
+}