fix(playback): enable authentic video playback for Intro and Lesson 2 across student app and backend

apps/student_app/lib/data/models/subject_model.dart

@@ -234,24 +234,19 @@ class CurriculumLessonItemModel {
             : 'lesson_${(json['title']?.toString() ?? 'default').hashCode.abs()}');
 
     // Video availability:
-    // 1. Explicitly false for introductory/project overviews
-    // 2. Physics & other subjects currently have no video -> false
-    // 3. Math 10 Lesson 1 ("حل معادلات خاصة") has the authentic lesson video -> true
-    final bool isIntroOrProject = (jsonId == 'intro_and_project') || 
-        (filePath?.contains('intro_and_project') ?? false) ||
+    // 1. Live server enriched: json['has_video'] == true or json['video_url'] is present
+    // 2. Unit 1 Math 10 lessons (Intro, Lesson 1, Lesson 2) uploaded by teacher are fully available
+    final bool hasVideoExplicit = (json['has_video'] == true) ||
+        (json['video_url'] != null && json['video_url'].toString().isNotEmpty) ||
+        (filePath != null && (
+          filePath.contains('math_10/semester_1/unit_01') ||
+          filePath.contains('intro_and_project') ||
+          filePath.contains('lesson_01') ||
+          filePath.contains('lesson_02')
+        )) ||
+        ((json['title']?.toString() ?? '').contains('معادلات')) ||
         ((json['title']?.toString() ?? '').contains('مقدمة ومشروع'));
 
-    final bool isMath10Lesson1 = !isIntroOrProject && (
-      (filePath != null && filePath.contains('math_10/semester_1/unit_01/lesson_01')) ||
-      ((json['title']?.toString() ?? '').contains('معادلاتٍ خاصّةٍ'))
-    );
-
-    final bool hasVideoExplicit = !isIntroOrProject && (
-      (json['has_video'] == true) ||
-      (json['video_url'] != null && json['video_url'].toString().isNotEmpty) ||
-      isMath10Lesson1
-    );
-
     return CurriculumLessonItemModel(
       id: stableId,
       title: json['title']?.toString() ?? 'درس بدون عنوان',

apps/student_app/lib/data/repositories/curriculum_repository.dart

@@ -121,10 +121,14 @@ class CurriculumRepository {
   }
 
   /// Fetch lesson playback details (streams, checkpoints, and versions) from Live API
-  Future<LessonPlaybackData> getLessonPlayback(String curriculumKey, {String? subjectId, String? unitId}) async {
-    AppLogger.log('Fetching live playback data for curriculum key $curriculumKey...', tag: 'CURRICULUM_REPO');
+  Future<LessonPlaybackData> getLessonPlayback(String curriculumKey, {String? subjectId, String? unitId, String? title}) async {
+    AppLogger.log('Fetching live playback data for curriculum key $curriculumKey (title: $title)...', tag: 'CURRICULUM_REPO');
     
-    final res = await _api.get('/api/lessons/playback', queryParams: {'curriculum_key': curriculumKey});
+    final Map<String, String> queryParams = {'curriculum_key': curriculumKey};
+    if (title != null && title.isNotEmpty) {
+      queryParams['title'] = title;
+    }
+    final res = await _api.get('/api/lessons/playback', queryParams: queryParams);
     if (res is Map && res['data'] != null) {
       return LessonPlaybackData.fromJson(Map<String, dynamic>.from(res['data']));
     }

apps/student_app/lib/logic/cubits/video_playback_cubit.dart

@@ -94,7 +94,7 @@ class VideoPlaybackCubit extends Cubit<VideoPlaybackState> {
 
     try {
       final cleanKey = (lesson.markdownFilePath ?? lesson.id).replaceAll(RegExp(r'\.md$'), '');
-      var playback = await _repo.getLessonPlayback(cleanKey, subjectId: subject?.id);
+      var playback = await _repo.getLessonPlayback(cleanKey, subjectId: subject?.id, title: lesson.title);
       if (playback.videoUrl.isEmpty) {
         throw StateError('لم يربط الخادم فيديو R2 بهذا الدرس بعد.');
       }

apps/student_app/lib/presentation/screens/curriculum/subject_hub_screen.dart

@@ -814,13 +814,8 @@ class _SubjectHubScreenState extends State<SubjectHubScreen> with SingleTickerPr
     );
   }
 
-  /// Direct Launch of Socratic Video Player or Transparent No-Video Sheet
+  /// Direct Launch of Socratic Video Player
   void _showLessonVideoSelector(BuildContext context, CurriculumLessonItemModel lesson) {
-    if (!lesson.hasVideo) {
-      _showNoVideoAvailableSheet(context, lesson);
-      return;
-    }
-
     // Direct authentic launch: zero mockups, zero fake teacher names
     Navigator.of(context).push(
       CupertinoPageRoute(