docs(payment): add Kyren Topup as international EasyPay provider option

Restructure the EasyPay recommendation block to present two options side
by side so users can pick by funding channel and settlement currency:

- Domestic / CNY — ZPay: official Alipay/WeChat API with 1.6% fee and
  T+1 automatic settlement (existing recommendation, expanded with fee
  and settlement details).
- International / USDT or USD — Kyren Topup (https://kyren.top): global
  payment stack supporting WeChat Pay and Alipay with local-currency
  checkout, USD settlement, and USDT/USD withdrawal. Fees: WeChat 2%,
  Alipay 2.5%, withdrawal 0.1% ($40 min / $150 max). Fills the gap for
  users who cannot use domestic Chinese channels or tolerate Stripe's
  6%+ fees.

Both recommendations share a single disclaimer at the end. The Chinese
heading uses "易支付" while the English one keeps "EasyPay".

docs/PAYMENT.md

@@ -28,7 +28,12 @@ Sub2API has a built-in payment system that enables user self-service top-up with
 
 > Alipay/WeChat Pay direct and EasyPay can coexist. Direct channels connect to payment APIs directly with lower fees; EasyPay aggregates through third-party platforms with easier setup.
 
-> **EasyPay Recommendation**: [ZPay](https://z-pay.cn/?uid=23808) (`https://z-pay.cn/?uid=23808`) is recommended as an EasyPay provider (link contains the referral code of [Sub2ApiPay](https://github.com/touwaeriol/sub2apipay) original author [@touwaeriol](https://github.com/touwaeriol) — feel free to remove it). ZPay supports **individual users** (no business license required) with up to 10,000 CNY daily transactions; business-licensed accounts have no limit. Please evaluate the security, reliability, and compliance of any third-party payment provider on your own — this project does not endorse or guarantee any of them.
+> **EasyPay Provider Recommendations**: Both options below are third-party aggregators compatible with the EasyPay protocol. Pick based on the funding channel and settlement currency you need:
+>
+> - **Domestic channel / CNY settlement** — [ZPay](https://z-pay.cn/?uid=23808) (`https://z-pay.cn/?uid=23808`): direct integration with official Alipay / WeChat Pay APIs, fee **1.6%**; funds go straight to the merchant account with **T+1 automatic settlement**. Supports **individual users** (no business license required) with up to 10,000 CNY daily transactions; business-licensed accounts have no limit. Link contains the referral code of [Sub2ApiPay](https://github.com/touwaeriol/sub2apipay) original author [@touwaeriol](https://github.com/touwaeriol) — feel free to remove it.
+> - **International channel / USDT or USD settlement** — [Kyren Topup](https://kyren.top/?code=SUB2API) (`https://kyren.top/?code=SUB2API`): a ready-to-launch global payment stack for AI startups with WeChat Pay and Alipay support, local-currency checkout, and USD settlement. Fees: WeChat 2%, Alipay 2.5%; withdrawal 0.1% (min $40, max $150), settled in **USDT or USD**. No qualification review required — sign up and use immediately, making it the lowest barrier to entry. Withdrawal threshold is relatively high, recommended for users **who do not use domestic Chinese payment channels, cannot tolerate Stripe's 6%+ fees, have high transaction volume, and have USD or USDT channels to receive withdrawn funds**. Link contains Sub2Api author [@Wei-Shaw](https://github.com/Wei-Shaw)'s referral code — feel free to remove it.
+>
+> Please evaluate the security, reliability, and compliance of any third-party payment provider on your own — this project does not endorse or guarantee any of them.
 
 ---
 

docs/PAYMENT_CN.md

@@ -28,7 +28,12 @@ Sub2API 内置支付系统，支持用户自助充值，无需部署独立的支
 
 > 支付宝官方 / 微信官方与 EasyPay 可以共存。官方渠道直接对接 API，资金直达商户账户，手续费更低；EasyPay 通过第三方平台聚合，接入门槛更低。
 
-> **EasyPay 推荐**：个人推荐 [ZPay](https://z-pay.cn/?uid=23808)（`https://z-pay.cn/?uid=23808`）作为 EasyPay 服务商（链接含 [Sub2ApiPay](https://github.com/touwaeriol/sub2apipay) 原作者 [@touwaeriol](https://github.com/touwaeriol) 的邀请码，介意可去掉）。ZPay 支持**个人用户**（无营业执照）每日 1 万元以内交易；拥有营业执照则无限额。支付渠道的安全性、稳定性及合规性请自行鉴别，本项目不对任何第三方支付服务商做担保或背书。
+> **易支付服务商推荐**：以下两家均为兼容易支付协议的第三方聚合支付，按资金通道与结算方式选择：
+>
+> - **国内渠道 / 人民币结算** — [ZPay](https://z-pay.cn/?uid=23808)（`https://z-pay.cn/?uid=23808`）：支付宝 / 微信官方 API 直连，手续费 **1.6%**；资金直达商家账户，**T+1 自动到账**。支持**个人用户**（无营业执照）每日 1 万元以内交易；拥有营业执照则无限额。链接含 [Sub2ApiPay](https://github.com/touwaeriol/sub2apipay) 原作者 [@touwaeriol](https://github.com/touwaeriol) 的邀请码，介意可去掉。
+> - **国际渠道 / USDT 或美元结算** — [启润支付](https://kyren.top/?code=SUB2API)（`https://kyren.top/?code=SUB2API`）：为 AI 项目提供低门槛国际收款通道，支持国际版微信支付与支付宝，本地货币支付、美元结算。手续费：微信 2%、支付宝 2.5%；提现 0.1%（最低 40 美元、最高 150 美元），以 **USDT 或美元**到账。无资质审核、注册即用，使用门槛最低；提现门槛略高，适合**不使用国内支付渠道、无法接受 Stripe 高达 6%+ 手续费、流水较大，且拥有美元或 USDT 渠道可接收提现资金**的用户。链接含 Sub2Api 作者 [@Wei-Shaw](https://github.com/Wei-Shaw) 邀请码，介意可去掉。
+>
+> 支付渠道的安全性、稳定性及合规性请自行鉴别，本项目不对任何第三方支付服务商做担保或背书。
 
 ---