feat: 新增项目公共工具包，包含日志、错误、数据库、缓存、公共proto

backend/shared/errors/errors.go

@@ -0,0 +1,46 @@
+package errors
+
+import (
+	"fmt"
+)
+
+type AppError struct {
+	Code    string
+	Message string
+	Err     error
+}
+
+func (e *AppError) Error() string {
+	if e.Err != nil {
+		return fmt.Sprintf("%s: %s (code: %s)", e.Message, e.Err.Error(), e.Code)
+	}
+	return fmt.Sprintf("%s (code: %s)", e.Message, e.Code)
+}
+
+func (e *AppError) Unwrap() error {
+	return e.Err
+}
+
+func NewAppError(code, message string, err error) *AppError {
+	return &AppError{
+		Code:    code,
+		Message: message,
+		Err:     err,
+	}
+}
+
+func NewBadRequestError(message string, err error) *AppError {
+	return NewAppError("BAD_REQUEST", message, err)
+}
+
+func NewInternalError(message string, err error) *AppError {
+	return NewAppError("INTERNAL_ERROR", message, err)
+}
+
+func NewNotFoundError(message string, err error) *AppError {
+	return NewAppError("NOT_FOUND", message, err)
+}
+
+func NewUnauthorizedError(message string, err error) *AppError {
+	return NewAppError("UNAUTHORIZED", message, err)
+}