Upload an attachment to a facility workflow record

Uploads a file attachment and associates it with a specific section row of the facility credentialing workflow. When to use: Use to attach supporting files (e.g., scanned certificates, signed forms) to a specific record within the workflow. The id form field identifies the target section row using the format {section}-{index} (e.g., licenses-0). To attach a file at the workflow level rather than a row level, use POST /facility-credentialing-workflows/{workflowId}/supporting-documents. Request: Multipart form data with fields: id (section-index string, required), file (binary, required), expirationDate (optional). Side effects: File is stored in Cloud Storage. The attachment record is created in the workflow. Returns: 201 Created with the attachment record. Returns 400 for a malformed request, 404 if the workflow is not found.