Upload Dispute Document

POST /v1/disputes/uploads

curl -X POST https://api.bachs.io/v1/disputes/uploads \
  -H "Authorization: Bearer sk_live_abc123xyz..." \
  -F "file=@/path/to/email-screenshot.pdf"

{
  "document_id": "upl_9f2c7b3d1e45",
  "file_name": "email-screenshot.pdf",
  "mime_type": "application/pdf",
  "file_size_bytes": 204800,
  "uploaded_at": "2026-03-09T10:00:00.000Z"
}