replaced generic "Event" label with substitution or lesson text

lib/view/pages/timetable/data/lesson_type_label.dart

@@ -1,4 +1,5 @@
 import '../../../../api/marianumconnect/queries/timetable_get_week/timetable_get_week_response.dart';
+import 'lesson_labels.dart';
 
 /// Derives a human-readable title from the Marianum-Connect `lessonType` for
 /// lessons that have no subject of their own (Aufsicht, Sprechstunde, …).
@@ -10,10 +11,20 @@ class LessonTypeLabel {
 
   static String forEntry(McTimetableEntry lesson) {
     final base = baseLabel(lesson.lessonType);
+    if (base == fallback) {
+      final text = entryText(lesson);
+      if (text != null) return text;
+    }
     final room = (lesson.rooms.firstOrNull ?? '').trim();
     return room.isEmpty ? base : '$room $base';
   }
 
+  /// Webuntis-Freitext eines fachlosen Eintrags („Klassenfahrt 8a“), der
+  /// aussagekräftiger ist als das generische „Event“.
+  static String? entryText(McTimetableEntry lesson) =>
+      collapseWhitespace(lesson.substitutionText) ??
+      collapseWhitespace(lesson.lessonText);
+
   /// Returns just the type wording without the room — useful when the caller
   /// renders the room separately (e.g. as a subtitle line).
   static String baseLabel(String lessonType) {