refactor: 移除 SQLite 支持，仅保留 MySQL

apps/server/src/attendance/attendance.lesson-session.spec.ts

@@ -577,9 +577,9 @@ describe('AttendanceService \u2014 DingTalk course attendance', () => {
       });
     // Simulate unique constraint on save
     sessionRepo.save.mockRejectedValueOnce(
-      Object.assign(new Error('UNIQUE constraint failed'), {
-        code: 'SQLITE_CONSTRAINT',
-        errno: undefined,
+      Object.assign(new Error('Duplicate entry'), {
+        code: 'ER_DUP_ENTRY',
+        errno: 1062,
       }),
     );
     classStudentRepo.find.mockResolvedValue([{ studentId: 1, student: { id: 1, name: '张三' } }]);