Added tool calling support (#731)

Co-authored-by: krut_ni <nils.kruthoff@dlr.de>
Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Provider/OpenAI/ResponsesFunctionTool.cs

@@ -0,0 +1,19 @@
+using System.Text.Json;
+
+namespace AIStudio.Provider.OpenAI;
+
+/// <summary>
+/// The flat function tool definition shape expected by the OpenAI Responses API.
+/// </summary>
+public sealed record ResponsesFunctionTool
+{
+    public string Type { get; init; } = "function";
+
+    public string Name { get; init; } = string.Empty;
+
+    public string Description { get; init; } = string.Empty;
+
+    public JsonElement Parameters { get; init; }
+
+    public bool Strict { get; init; }
+}