Added PowerPoint templates to the Slide Assistant (#1055)

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

app/MindWork AI Studio/Assistants/SlideBuilder/TemplateSlideExtensions.cs

@@ -0,0 +1,30 @@
+using AIStudio.Tools.PowerPoint;
+
+namespace AIStudio.Assistants.SlideBuilder;
+
+internal static class TemplateSlideExtensions
+{
+    private static string TB(string fallbackEN) => Tools.PluginSystem.I18N.I.T(fallbackEN, typeof(TemplateSlideExtensions).Namespace, nameof(TemplateSlideExtensions));
+
+    /// <summary>
+    /// How many characters of its title a slide of the template shows in its label.
+    /// </summary>
+    private const int MAX_SLIDE_TITLE_CHARACTERS = 60;
+
+    /// <summary>
+    /// How the forms name a slide of the template: by its number and its title, and what is special about it.
+    /// </summary>
+    /// <remarks>
+    /// The title tells the slides apart at a glance, since a template rarely gives its slides more
+    /// than a title. A long one is cut, so that the label stays on one line.
+    /// </remarks>
+    public static string Label(this TemplateSlide slide)
+    {
+        var title = slide.Title.Length > MAX_SLIDE_TITLE_CHARACTERS ? $"{slide.Title[..MAX_SLIDE_TITLE_CHARACTERS].TrimEnd()}…" : slide.Title;
+        var label = title.Length > 0 ? string.Format(TB("Slide {0}: {1}"), slide.Number, title) : string.Format(TB("Slide {0}"), slide.Number);
+        if (slide.IsHidden)
+            label = $"{label} ({TB("hidden")})";
+
+        return label;
+    }
+}