🔗 短链接生成

POST /api/shorten
Content-Type: application/json

{
  "url": "https://example.com",
  "custom_code": "abc123",
  "password": "123456",
  "expires_days": 30
}

POST /api/upload   (multipart/form-data: image)
GET /api/urls
GET /api/stats/<code>
GET /api/qrcode/<code>
DELETE /api/delete/<code>
POST /api/verify-password
GET /<code>          公开跳转 / 图片页
GET /<code>/raw      公开原图