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/EmbeddedConversation.cs

@@ -0,0 +1,57 @@
+namespace AIStudio.Chat.Embedded;
+
+/// <summary>
+/// An embedded chat as EmbeddedChatService keeps it, with whether the model answers in it right now.
+/// </summary>
+public sealed class EmbeddedConversation
+{
+    /// <summary>
+    /// The ID of the chat.
+    /// </summary>
+    public required Guid ChatId { get; init; }
+
+    /// <summary>
+    /// The assistant which shows the chat. Its requests register in AssistantSessionService under it.
+    /// </summary>
+    public required Tools.Components Component { get; init; }
+
+    /// <summary>
+    /// Where the chat lives.
+    /// </summary>
+    public required IEmbeddedChatStore Store { get; init; }
+
+    /// <summary>
+    /// The thread of the chat, or null when this version cannot open the stored one.
+    /// </summary>
+    public ChatThread? Thread { get; internal set; }
+
+    /// <summary>
+    /// Whether the model answers in the chat right now.
+    /// </summary>
+    public bool IsRunning { get; internal set; }
+
+    /// <summary>
+    /// Whether the chat could be opened.
+    /// </summary>
+    public bool IsAvailable => this.Thread is not null;
+
+    /// <summary>
+    /// Whether the chat holds any message the user sees.
+    /// </summary>
+    public bool HasVisibleMessages => this.Thread?.Blocks.Any(block => !block.HideFromUser) ?? false;
+
+    /// <summary>
+    /// How many messages the user wrote in the chat, those the user does not see left aside.
+    /// </summary>
+    public int UserMessageCount => this.Thread?.Blocks.Count(block => block is { Role: ChatRole.USER, HideFromUser: false }) ?? 0;
+
+    /// <summary>
+    /// The first message of the user which the user sees, or null before it.
+    /// </summary>
+    public ContentBlock? FirstUserMessage => this.Thread?.Blocks.FirstOrDefault(block => block is { Role: ChatRole.USER, HideFromUser: false });
+
+    /// <summary>
+    /// Whether the chat holds an answer of the model which the user sees.
+    /// </summary>
+    public bool HasAnswer => this.Thread?.Blocks.Any(block => block is { Role: ChatRole.AI, HideFromUser: false }) ?? false;
+}