Bulk fetch URLs

Enqueues multiple URLs for HTTP fetching. Results delivered via webhook. Does not support options that require page rendering (cookies, wait_for_selector, etc.). **Limits:** request bodies are guarded in a two-tier shape. A streamed body with no `Content-Length` header is capped at 2 MB before your API key is checked; a body that declares `Content-Length` is instead bounded there by a 20 MB fail-safe (not the real limit — see below), since that branch reads nothing until your key is verified. Once your key is verified, a second check re-gates the body against your account's own `max_bulk_size` (at this endpoint's per-item override budget), which reaches 16.8 MB for the largest documented account. A standard-plan account's effective ceiling is 2 MB; either tier's overrun returns a `400` with error code `request_too_large`.

curl -X POST https://api.bytekit.com/v1/fetch/bulk \
  -H "Authorization: Bearer sk_live_your_api_key_here"

{
  "id": "bulk_01j9abc123",
  "status": "processing",
  "total": 0,
  "completed": 0,
  "failed": 0,
  "created_at": "2019-08-24T14:15:22Z",
  "completed_at": "2019-08-24T14:15:22Z",
  "total_credits_charged": 0,
  "estimated_credits": 0,
  "webhook_url": "string"
}