后台增加撤销用户实名功能

实名姓名与收款账户不一致会导致收款码登记失败，新增后台撤销实名能力：
- 新增 user:revoke_realname 权限，授予超级管理员与运营角色
- 撤销时重置用户实名状态为未认证并删除实名记录，使其可重新认证，写入审计日志
- 用户管理页新增实名状态列与"撤销实名"操作（含原因弹窗）

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/internal/router/router.go

@@ -482,6 +482,7 @@ func New(cfg config.Config, deps Dependencies, logger *zap.Logger) *gin.Engine {
 			adminRoutes.POST("/users/:id/freeze", requirePerm("user:freeze"), adminUserHandler.Freeze)
 			adminRoutes.POST("/users/:id/unfreeze", requirePerm("user:unfreeze"), adminUserHandler.Unfreeze)
 			adminRoutes.POST("/users/:id/deposit-free-quota", requirePerm("user:deposit_free"), adminUserHandler.SetDepositFreeQuota)
+			adminRoutes.POST("/users/:id/revoke-realname", requirePerm("user:revoke_realname"), adminUserHandler.RevokeRealname)
 			adminRoutes.GET("/orders", requirePerm("order:view"), orderHandler.AdminList)
 			adminRoutes.GET("/orders/:id", requirePerm("order:view"), orderHandler.AdminDetail)
 			adminRoutes.GET("/orders/:id/handoff-records", requirePerm("order:view"), orderHandler.AdminHandoffRecords)