Implement verified curriculum, video review, watch sessions, ledger safeguards, and remove demo data

backend/app/Services/CurriculumService.php

@@ -28,56 +28,11 @@ class CurriculumService
     }
 
     /**
-     * Runtime migration: add is_system_curriculum (and related columns) to `courses`
-     * if they are missing. Safe to call multiple times — uses IF NOT EXISTS / IGNORE.
+     * Compatibility hook. Course schema is managed by migrations, never by requests.
      */
     public static function ensureSystemCurriculumColumn(): void
     {
-        static $ran = false;
-        if ($ran) return;
-        $ran = true;
-
-        try {
-            // Check whether the column exists to avoid noisy ALTER errors on every request
-            $row = Database::selectOne(
-                "SELECT COUNT(*) as cnt FROM information_schema.COLUMNS
-                 WHERE TABLE_SCHEMA = DATABASE()
-                   AND TABLE_NAME   = 'courses'
-                   AND COLUMN_NAME  = 'is_system_curriculum'
-                 LIMIT 1"
-            );
-
-            if (empty($row['cnt'])) {
-                Database::query(
-                    "ALTER TABLE `courses`
-                     ADD COLUMN `is_system_curriculum` TINYINT(1) NOT NULL DEFAULT 0
-                         COMMENT 'الدورة الرئيسية للمنهاج الوزاري'
-                     AFTER `is_school_exclusive`"
-                );
-            }
-
-            // Also ensure grade_level + stream columns exist (for student filtering)
-            $gradeRow = Database::selectOne(
-                "SELECT COUNT(*) as cnt FROM information_schema.COLUMNS
-                 WHERE TABLE_SCHEMA = DATABASE()
-                   AND TABLE_NAME   = 'courses'
-                   AND COLUMN_NAME  = 'grade_level'
-                 LIMIT 1"
-            );
-            if (empty($gradeRow['cnt'])) {
-                Database::query(
-                    "ALTER TABLE `courses`
-                     ADD COLUMN `grade_level` VARCHAR(50) DEFAULT NULL
-                         COMMENT 'المرحلة الدراسية مثل: tawjihi_2008'
-                     AFTER `is_system_curriculum`,
-                     ADD COLUMN `stream` ENUM('scientific','literary','vocational','general') DEFAULT NULL
-                         COMMENT 'الفرع الدراسي'
-                     AFTER `grade_level`"
-                );
-            }
-        } catch (\Throwable $e) {
-            error_log('[CurriculumService] ensureSystemCurriculumColumn error: ' . $e->getMessage());
-        }
+        // Intentionally empty. Run backend/scripts/run_migrations.php before serving.
     }
 
     /**