feat: 拆分邮件通知选项，根据会员权益显示

- 翻译完成邮件通知（所有用户）
- 鮮件带附件发送（VIP专属，free用户显示需VIP）
- 会员到期提醒（仅VIP用户显示）
- 添加 notify_with_attachment 字段
- 更新各等级权益：email_notify/email_attachment

app.py

@@ -223,6 +223,8 @@ def pricing():
         'priority_queue': '优先处理队列',
         'custom_instruction': '自定义翻译要求',
         'api_access': 'API接口调用',
+        'email_notify': '邮件通知',
+        'email_attachment': '邮件附件发送',
     }
     
     # 从数据库读取动态配置的会员套餐
@@ -289,10 +291,15 @@ def profile():
     daily_remaining = limits['daily_translations'] - user.daily_count if limits['daily_translations'] > 0 else '无限'
     max_pages = limits['max_pages'] if limits['max_pages'] > 0 else '无限'
     
+    # 检查是否有邮件附件权限
+    user_features = limits.get('features', [])
+    has_email_attachment = 'email_attachment' in user_features or user_features == ['all']
+    
     return render_template('profile.html', 
         user=user,
         daily_remaining=daily_remaining,
-        max_pages=max_pages
+        max_pages=max_pages,
+        has_email_attachment=has_email_attachment
     )
 
 
@@ -876,6 +883,14 @@ def update_settings():
         user.notify_on_complete = data.get('notify_on_complete', True)
     if 'notify_on_expire' in data:
         user.notify_on_expire = data.get('notify_on_expire', True)
+    if 'notify_with_attachment' in data:
+        # 检查是否有附件权限
+        limits = USER_LIMITS.get(user.user_type, USER_LIMITS['free'])
+        user_features = limits.get('features', [])
+        if 'email_attachment' in user_features or user_features == ['all']:
+            user.notify_with_attachment = data.get('notify_with_attachment', False)
+        else:
+            return jsonify({'error': '邮件附件功能需VIP会员', 'feature': 'email_attachment'}), 403
     if 'email_notify' in data:
         user.email_notify = data.get('email_notify', True)