Sessions: Sidebar, Session-Wechsel, Archivieren-Button, alles session-bezogen

Models/ChatModels.cs

@@ -22,4 +22,7 @@ public class ChatRequest
 
     [JsonPropertyName("systemPrompt")]
     public string SystemPrompt { get; set; } = "";
+
+    [JsonPropertyName("sessionId")]
+    public string SessionId { get; set; } = "";
 }