added teacher-focused lesson sheet with direct class and teacher timetable links

lib/storage/modules_settings.dart

@@ -10,12 +10,16 @@ class ModulesSettings {
   List<Modules> hiddenModules;
   bool autoFillBottomBar;
   int fixedBottomBarSlots;
+  // Set once the teacher module defaults were applied, so a module the teacher
+  // re-enables afterwards stays visible.
+  bool teacherDefaultsApplied;
 
   ModulesSettings({
     required this.moduleOrder,
     required this.hiddenModules,
     this.autoFillBottomBar = true,
     this.fixedBottomBarSlots = 3,
+    this.teacherDefaultsApplied = false,
   });
 
   factory ModulesSettings.fromJson(Map<String, dynamic> json) =>