Add one image URL reference to a pack
image_url and inferred metadata on the pack.url as image_url.1-255 chars). Default: "image".content_type from URL extension (.png, .gif, .webp,
.heic, .heif, .avif) and defaults to image/jpeg when unknown.400 missing_pack_id - path param missing400 invalid_json - body is not valid JSON422 invalid_payload - schema validation failed404 not_found - pack is missing/outside mutable key scope401 - authentication failed (missing/invalid/revoked token)402 subscription_required - active Creator/Professional/Business plan required403 tier_not_allowed - Scheduler tier cannot use Partner API500 pack_image_add_failed - unexpected insertion failure