{"service":"payment link service","docs":"/docs","openapi":"/openapi.json","endpoints":{"POST /api/v1/payment-links":"建立支付連結（order_no 唯一，重複回 409）","POST /callback（由服務主動調用）":"支付結果回調商戶 callback_url","GET /api/v1/payment-channels":"查詢可用支付渠道","GET /healthz":"健康檢查"}}