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/Assistants/ModelComparison/ModelComparisonPresetChoice.cs

@@ -0,0 +1,30 @@
+using AIStudio.Settings.DataModel;
+
+namespace AIStudio.Assistants.ModelComparison;
+
+/// <summary>
+/// Decides which preset the mode Answer Variance works in, since it always works in one.
+/// </summary>
+public static class ModelComparisonPresetChoice
+{
+    /// <summary>
+    /// Chooses the preset the mode Answer Variance opens with, and the one it continues with after a preset was deleted: the
+    /// preselected preset of the options, or else the first one.
+    /// </summary>
+    /// <remarks>
+    /// An assistant session which the page restores brings back the preset of its own instead, because the form it
+    /// restores belongs to that preset.
+    /// </remarks>
+    /// <param name="presets">The presets, in the order the list shows them.</param>
+    /// <param name="options">The options of the assistant.</param>
+    /// <returns>The ID of the preset, or null when there is none, and a new one is needed.</returns>
+    public static Guid? Choose(IReadOnlyList<ModelComparisonPreset> presets, DataModelComparison options)
+    {
+        if (options.PreselectOptions
+            && Guid.TryParse(options.PreselectedPresetId, out var preselectedId)
+            && presets.Any(preset => preset.Id == preselectedId))
+            return preselectedId;
+
+        return presets.Count > 0 ? presets[0].Id : null;
+    }
+}