feat(grade10): add chemistry, biology, and earth sciences virtual labs, fix video CDN playback, teacher submissions SQL, and enable authenticated lesson reading

backend/app/Services/StudentAccessControlService.php

@@ -102,8 +102,10 @@ class StudentAccessControlService
         // أما الطلبة المستقلون وحسابات التجربة والتعلم الحر، فيتم تحديث صفهم النشط تلقائياً وفق المحتوى المختار
         $isCohortLocked = !empty($student['is_school_sponsored']) || !empty($student['school_id']);
         if ($activeStudentGrade !== $normalizedTargetGrade) {
-            if (!$isCohortLocked && !empty($student['id']) && $allowSideEffects) {
-                Database::query("UPDATE students SET grade_level = ? WHERE id = ?", [$normalizedTargetGrade, (int)$student['id']]);
+            if (!$isCohortLocked && !empty($student['id'])) {
+                if ($allowSideEffects) {
+                    Database::query("UPDATE students SET grade_level = ? WHERE id = ?", [$normalizedTargetGrade, (int)$student['id']]);
+                }
                 $activeStudentGrade = $normalizedTargetGrade;
             } else {
                 $targetGradeName = self::getGradeDisplayName($normalizedTargetGrade);