docs: 支付模块开发文档 + git 域名更新

- 新增 backend/design/支付模块架构概览.md
- 新增 backend/design/支付模块数据库设计.md (21张表 DDL)
- 新增 backend/design/支付模块接口设计.md
- git.dev.vifo.cc → git.vifo.cc 全局替换

ai-skills/issue-workflow.md

@@ -8,14 +8,14 @@
 ```bash
 TOKEN=$(cat ~/.config/gitea/token)
 curl -s -H "Authorization: token ${TOKEN}" \
-  "https://git.dev.vifo.cc/api/v1/repos/{owner}/{repo}/issues/{id}"
+  "https://git.vifo.cc/api/v1/repos/{owner}/{repo}/issues/{id}"
 ```
 
 也可以列出当前仓库所有未关闭的工单：
 ```bash
 TOKEN=$(cat ~/.config/gitea/token)
 curl -s -H "Authorization: token ${TOKEN}" \
-  "https://git.dev.vifo.cc/api/v1/repos/{owner}/{repo}/issues?state=open"
+  "https://git.vifo.cc/api/v1/repos/{owner}/{repo}/issues?state=open"
 ```
 
 ### 2. 分析需求
@@ -55,7 +55,7 @@ curl -s -X POST \
   -H "Authorization: token ${TOKEN}" \
   -H "Content-Type: application/json" \
   -d '{"body": "✅ 已完成\n\n完成内容..."}' \
-  "https://git.dev.vifo.cc/api/v1/repos/{owner}/{repo}/issues/{id}/comments"
+  "https://git.vifo.cc/api/v1/repos/{owner}/{repo}/issues/{id}/comments"
 ```
 
 ### 6. 关闭工单
@@ -66,7 +66,7 @@ curl -s -X PATCH \
   -H "Authorization: token ${TOKEN}" \
   -H "Content-Type: application/json" \
   -d '{"state": "closed"}' \
-  "https://git.dev.vifo.cc/api/v1/repos/{owner}/{repo}/issues/{id}"
+  "https://git.vifo.cc/api/v1/repos/{owner}/{repo}/issues/{id}"
 ```
 
 ## 跨仓库提工单
@@ -91,7 +91,7 @@ curl -s -X POST \
   -H "Authorization: token ${TOKEN}" \
   -H "Content-Type: application/json" \
   -d @/tmp/issue.json \
-  "https://git.dev.vifo.cc/api/v1/repos/rui/rui-framework/issues"
+  "https://git.vifo.cc/api/v1/repos/rui/rui-framework/issues"
 ```
 
 ## 提交规范