Fixed page numbers being guessed from the text instead of read from the metadata

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

@@ -1,3 +1,9 @@
 namespace AIStudio.Tools.Services;
 
-public sealed record ArbitraryFileDataSegment(string Content, int TokenCount);
+/// <summary>
+/// One piece of an extracted file, as the runtime delivered it.
+/// </summary>
+/// <param name="Content">The extracted text.</param>
+/// <param name="TokenCount">The number of tokens of that text.</param>
+/// <param name="PageNumber">The page that text came from, or null when it has none. Presentations and spreadsheets have none.</param>
+public sealed record ArbitraryFileDataSegment(string Content, int TokenCount, int? PageNumber);