merge: 合并 test 分支到 test-dev，解决冲突

解决的冲突文件：
- wire_gen.go: 合并 ConcurrencyService/CRSSyncService 参数和 userAttributeHandler
- gateway_handler.go: 合并 pkg/errors 和 antigravity 导入
- gateway_service.go: 合并 validateUpstreamBaseURL 和 GetAvailableModels
- config.example.yaml: 合并 billing/turnstile 配置和额外 gateway 选项

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/internal/handler/dto/mappers.go

@@ -10,7 +10,6 @@ func UserFromServiceShallow(u *service.User) *User {
 		ID:            u.ID,
 		Email:         u.Email,
 		Username:      u.Username,
-		Wechat:        u.Wechat,
 		Notes:         u.Notes,
 		Role:          u.Role,
 		Balance:       u.Balance,

backend/internal/handler/dto/types.go

@@ -6,7 +6,6 @@ type User struct {
 	ID            int64     `json:"id"`
 	Email         string    `json:"email"`
 	Username      string    `json:"username"`
-	Wechat        string    `json:"wechat"`
 	Notes         string    `json:"notes"`
 	Role          string    `json:"role"`
 	Balance       float64   `json:"balance"`