Added PowerPoint templates to the Slide Assistant (#1055)

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

app/MindWork AI Studio/Tools/PowerPoint/TextCapacity.cs

@@ -0,0 +1,12 @@
+namespace AIStudio.Tools.PowerPoint;
+
+/// <summary>
+/// How much text fits into a slot, estimated from its size and its font size.
+/// </summary>
+/// <remarks>
+/// An estimate on purpose: the real width of a line depends on the font and the words. It tells the
+/// model how much to write, and the check of its answer how much is clearly too much.
+/// </remarks>
+/// <param name="Lines">How many lines fit, or how many rows for a table.</param>
+/// <param name="CharactersPerLine">How many characters fit into one line, across the whole width.</param>
+internal readonly record struct TextCapacity(int Lines, int CharactersPerLine);