Add tiered commissions

Creates tiered commission tiers for a listing, replacing any existing tiers. Tiered and flat commissions are mutually exclusive. Returns 422 when validation fails (percent out of 0-100, negative amounts, an empty tier, or a missing tier-1 breakpoint when a second tier is supplied).

Validation & Requirements

Required Parameters

• listingGuid (path, string, format=guid)
• tieredCommissions (body, object)

Required JSON Body Fields

• None

Validations

• Invalid GUID values in *Guid/*Guids fields return 422 Unprocessable Entity.
• Invalid date values in *date* fields return 422 Unprocessable Entity.
• Missing required request body returns 422 Unprocessable Entity with Missing request body..
• Additional business-rule validation may return 422 with details in the errors array.

Integration Requirement

• Retrieve the corresponding ...Form endpoint immediately before write operations to get current dynamic required fields and allowed values.