Added a way to read what the AI received from your sources (#1100)

Co-authored-by: Thorsten Sommer <SommerEngineering@users.noreply.github.com>

app/MindWork AI Studio/Tools/Services/PassageRange.cs

@@ -0,0 +1,14 @@
+namespace AIStudio.Tools.Services;
+
+/// <summary>
+/// The rows or lines a passage spans, as far as it names them, cf. DataSourceLocalRetrievalService.LocatePassage.
+/// </summary>
+/// <param name="Start">The first row or line, or null when the passage names none.</param>
+/// <param name="End">The last row or line, or null when the passage does not go on beyond its first one.</param>
+internal readonly record struct PassageRange(int? Start, int? End)
+{
+    /// <summary>
+    /// The passage names no rows or lines.
+    /// </summary>
+    public static readonly PassageRange NONE = new(null, null);
+}