Returns a paginated list of project affiliates with per-conversion multilevel commission rates (r1–r4 as fractions 0–1),
derived from tier payout configuration for each affiliate's effective tier (same business logic as the dashboard
GET /api/v1/projects/{projectId}/affiliates/commission-rates route).

Project scope: resolved from the project API key in Authorization: Bearer <api_key>.

Query filters: same optional parameters as the dashboard affiliates list (page, per_page, query, sort_by, sort_order,
statuses, regions, audiences, tiers, tax_statuses, dateRange, dateFrom, dateTo).

Required API Key Scope: service_role