feat: Reduce minimum audit log deletion period to 6 days and update enrollment last access only for active enrollments.

Backend/src/controllers/AuditController.ts

@@ -169,8 +169,8 @@ export class AuditController {
             throw new ValidationError('No token provided');
         }
 
-        if (days < 30) {
+        if (days < 6) {
-            throw new ValidationError('Cannot delete logs newer than 30 days');
+            throw new ValidationError('Cannot delete logs newer than 6 days');
         }
 
         const deleted = await auditService.deleteOldLogs(days);

Backend/src/services/CoursesStudent.service.ts

@@ -341,6 +341,7 @@ export class CoursesStudentService {
             }
 
             // Update last_accessed_at (fire-and-forget — ไม่ block response)
+            if (enrollment.status === 'ENROLLED') {
                 prisma.enrollment.update({
                     where: {
                         unique_enrollment: {
@@ -350,6 +351,7 @@ export class CoursesStudentService {
                     },
                     data: { last_accessed_at: new Date() },
                 }).catch(err => logger.warn(`Failed to update last_accessed_at: ${err}`));
+            }
 
             // Get all lesson progress for this user and course
             const lessonIds = course.chapters.flatMap(ch => ch.lessons.map(l => l.id));