Douyin Posts by user API

Please help me write a data collection script with the EveryInfra Douyin Posts by user endpoint (douyin/user_posts).

Endpoint contract:
- Request: POST https://api.everyinfra.com/api/v1/social with the header Authorization: Bearer <API key>. Read the key from the EVERYINFRA_API_KEY environment variable and never hard-code it.
- In the request body, set platform to douyin and action to user_posts, and put the parameters inside params.
- Required parameters:
  - user_id: The Douyin user's secUid string (typically starting with MS4w), not a nickname or short numerical Douyin ID. Used to identify accounts for profile and user_posts actions.
- Optional parameters:
  - page_token: Page token for user_posts: send an empty string page_token="" to start from the newest page, then pass back each response's next_page_token exactly as received, keeping the other parameters unchanged.
  - since: Sets a lower bound for video publish dates in profile and user_posts actions using the YYYY-MM-DD format. Filters videos retrieved for the request rather than account creation date.
  - limit: The most rows to return in this call, an integer from 1 to 100. The default applies when you leave it out, and a call can return fewer rows. Larger values return 422 before any charge. (default: 20)
- Returns a list of records. Main fields of each record: next_page_token (Page token (user_posts / comments): pas…), id, url, text, media_type (Media type: video, or image for image p…), video_url (Video playback URL (signed, expires), like_count, comment_count, share_count, collect_count, author_name, author_id; 41 fields in total, full list at https://api.everyinfra.com/api/v1/social/catalog?platform=douyin.
- Example request body:
{
  "platform": "douyin",
  "action": "user_posts",
  "params": {
    "user_id": "https://www.douyin.com/user/MS4wLjABAAAAk1tZ-L085zZf2yW_H5dnVFZWyk8Rt8v4RAvf9KhTyPoVdMDxTs7Q_rvgTJGWXezS"
  }
}
- Price: $0.56 per 1,000 requests; failed and empty results are not charged.
- For dozens or hundreds of targets, add "mode": "async" to the body: you get a job_id at once and poll GET https://api.everyinfra.com/api/v1/jobs/{job_id} for the result.
- On 422, fix the request using the suggested parameter names and allowed values in the error; on 429 or 503, wait for Retry-After and try again.

Before writing code, ask me which targets I need, how many, which fields, and what output format I want; then confirm the plan and the rough cost with me.