去水印解析 API

1. 将参数按key升序排列（不含sign）
2. 拼接成 key1=value1&key2=value2&key=YOUR_APP_SECRET
3. 对拼接字符串进行MD5加密并转大写

示例：
params = {app_id: "WM123456", url: "https://...", timestamp: 1234567890}
signStr = "app_id=WM123456×tamp=1234567890&url=https://...&key=YOUR_APP_SECRET"
sign = MD5(signStr).toUpperCase()

{
    "code": 0,
    "msg": "success",
    "data": {
        "type": "video",
        "platform": "douyin",
        "title": "视频标题",
        "author": "作者名称",
        "avatar": "作者头像URL",
        "cover": "封面图URL",
        "video_url": "无水印视频URL",
        "music_url": "背景音乐URL",
        "images": []
    },
    "time": "123ms"
}

{
    "code": 0,
    "msg": "success",
    "data": {
        "balance": 99.50,
        "total_calls": 1000,
        "today_calls": 50,
        "daily_limit": 0
    }
}