Added the visual briefing assistant (#893)

app/MindWork AI Studio/Assistants/VisualBriefing/VisualBriefingSourceHandles.cs

@@ -0,0 +1,24 @@
+namespace AIStudio.Assistants.VisualBriefing;
+
+/// <summary>
+/// Maps briefing sources to stable short handles used by model contracts.
+/// </summary>
+internal static class VisualBriefingSourceHandles
+{
+    /// <summary>
+    /// Orders sources canonically and pairs them with their handles.
+    /// </summary>
+    /// <param name="manifest">The briefing manifest.</param>
+    /// <returns>The handles and sources in canonical order.</returns>
+    internal static IReadOnlyList<(string Handle, VisualBriefingSource Source)> Map(VisualBriefingManifest manifest) =>
+    [
+        .. manifest.Sources.OrderBy(source => source.SourceId).Select((source, index) => (Handle: Handle(index), Source: source))
+    ];
+
+    /// <summary>
+    /// Names the handle at one zero-based canonical source position.
+    /// </summary>
+    /// <param name="index">The zero-based canonical position.</param>
+    /// <returns>The source handle.</returns>
+    private static string Handle(int index) => $"s{index + 1}";
+}