- Add recharge_fee_rate system setting (percentage fee on top of recharge amount) - Full backend chain: config constant, PaymentConfig struct, update validation, read/write persistence, DTO, handler GET/PUT responses - Frontend: settings input with preview, i18n (zh/en), API types - Fix provider card toggle layout: labels above switches to save width - Fix Chinese translation: "EasyPay" → "易支付" in provider description
Add a full payment and subscription system supporting EasyPay (Alipay/WeChat), Stripe, and direct Alipay/WeChat Pay providers with multi-instance load balancing.
