VK Posts by user API

Please help me write a data collection script with the EveryInfra VK Posts by user endpoint (vk/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 vk and action to user_posts, and put the parameters inside params.
- Required parameters:
  - username: Identifies the target public profile or community for the user_posts action. Accepts a short name, a numeric club ID, a numeric owner ID, or a full profile/wall URL (e.g., vk.com links), rather than just personal user ha…
- Optional parameters:
  - 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: id, url, text, posted_at, like_count, comment_count, repost_count, view_count, media_urls, author_id, author_name, author_type; 14 fields in total, full list at https://api.everyinfra.com/api/v1/social/catalog?platform=vk.
- Example request body:
{
  "platform": "vk",
  "action": "user_posts",
  "params": {
    "username": "durov"
  }
}
- Price: $1.39 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.