feat: 微信V3 + 支付宝手机站/UA自适应 + 业务对接(签名下单/webhook) + 通用多业务

- 微信支付 V3 Native 渠道 (wechat.go)：Native下单/回调AES-GCM解密验签/查单
- 支付宝：手机网站支付 wap.pay + 按 UA 自适应(PC page.pay扫码 / 手机拉App)；qr_pay_mode=2 完整扫码收银台
- 业务对接：下单接口扩展(biz_system/biz_ref/return_url)+ HMAC 签名鉴权；支付成功 webhook 主动推送业务方 + 60s 重试 + BizNotifyLog
- 通用多业务：config.biz 改 map，加业务只改配置(BIZ_<SYS>_SECRET/_CALLBACK_URL)
- seedPlans：四档真实套餐 + promo_first_month(¥1) + test_liandiao(0.01)，均挂 biz_code；/products 暴露 biz_code
- 删除沙箱 pay.html；对接设计文档入 docs

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019UQmqWmV67sXGLrb3U1XXn

go.sum

@@ -1,3 +1,5 @@
+github.com/agiledragon/gomonkey v2.0.2+incompatible h1:eXKi9/piiC3cjJD1658mEE2o3NjkJ5vDLgYjCQu0Xlw=
+github.com/agiledragon/gomonkey v2.0.2+incompatible/go.mod h1:2NGfXu1a80LLr2cmWXGBDaHEjb1idR6+FVlX5T3D9hw=
 github.com/bytedance/gopkg v0.1.3 h1:TPBSwH8RsouGCBcMBktLt1AymVo2TVsBVCY4b6TnZ/M=
 github.com/bytedance/gopkg v0.1.3/go.mod h1:576VvJ+eJgyCzdjS+c4+77QF3p7ubbtiKARP3TxducM=
 github.com/bytedance/sonic v1.15.0 h1:/PXeWFaR5ElNcVE84U0dOHjiMHQOwNIx3K4ymzh/uSE=
@@ -109,6 +111,7 @@ github.com/stretchr/objx v0.5.2/go.mod h1:FRsXN1f5AsAjCGJKqEizvkpNtU+EGNCLh3NxZ/
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.8.0/go.mod h1:yNjHg4UonilssWZ8iaSj1OCr/vHnekPRkoO+kdMU+MU=
+github.com/stretchr/testify v1.8.1/go.mod h1:w2LPCIKwWwSfY2zedu0+kehJoqGctiVI29o6fzry7u4=
 github.com/stretchr/testify v1.8.4/go.mod h1:sz/lmYIOXD/1dqDmKjjqLyZ2RngseejIcXlSw2iwfAo=
 github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
 github.com/stretchr/testify v1.11.1 h1:7s2iGBzp5EwR7/aIZr8ao5+dra3wiQyKjjFuvgVKu7U=
@@ -119,6 +122,8 @@ github.com/twitchyliquid64/golang-asm v0.15.1 h1:SU5vSMR7hnwNxj24w34ZyCi/FmDZTkS
 github.com/twitchyliquid64/golang-asm v0.15.1/go.mod h1:a1lVb/DtPvCB8fslRZhAngC2+aY1QWCk3Cedj/Gdt08=
 github.com/ugorji/go/codec v1.3.1 h1:waO7eEiFDwidsBN6agj1vJQ4AG7lh2yqXyOXqhgQuyY=
 github.com/ugorji/go/codec v1.3.1/go.mod h1:pRBVtBSKl77K30Bv8R2P+cLSGaTtex6fsA2Wjqmfxj4=
+github.com/wechatpay-apiv3/wechatpay-go v0.2.21 h1:uIyMpzvcaHA33W/QPtHstccw+X52HO1gFdvVL9O6Lfs=
+github.com/wechatpay-apiv3/wechatpay-go v0.2.21/go.mod h1:A254AUBVB6R+EqQFo3yTgeh7HtyqRRtN2w9hQSOrd4Q=
 go.mongodb.org/mongo-driver/v2 v2.5.0 h1:yXUhImUjjAInNcpTcAlPHiT7bIXhshCTL3jVBkF3xaE=
 go.mongodb.org/mongo-driver/v2 v2.5.0/go.mod h1:yOI9kBsufol30iFsl1slpdq1I0eHPzybRWdyYUs8K/0=
 go.uber.org/mock v0.6.0 h1:hyF9dfmbgIX5EfOdasqLsWD6xqpNZlXblLB/Dbnwv3Y=