fix: notifications page crash + email code dev-mode false error

- notifications.js: EventOptions(current) referenced undefined 'Current'
  (case typo) -> ReferenceError crashed add/edit modal, page unusable
- auth.js send-verify-code: dev mode (SMTP down) deleted captcha row before
  returning code, so register always failed with '验证码无效或已过期'
  even with correct code. Keep row; it's deleted after successful verify.

backend/routes/auth.js

@@ -29,7 +29,8 @@ router.post('/send-verify-code', async (req, res) => {
       code,
     });
     if (!sent) {
-      await query('DELETE FROM captchas WHERE id = ?', [codeId]);
+      // SMTP 未配置/发送失败(dev 模式): 保留验证码记录, 前端直接显示验证码;
+      // 注册校验通过后会自动删除, 不会出现"验证码正确却报错"的问题
       return res.status(200).json({ code_id: codeId, code, dev: true });
     }
     res.json({ code_id: codeId, message: '验证码已发送' });