feat: 实现公共工具包，包括日志、错误处理、数据库和缓存

backend/shared/pkg/errors/errors.go

@@ -0,0 +1,96 @@
+package errors
+
+import (
+	"errors"
+	"fmt"
+)
+
+// 错误类型定义
+var (
+	ErrNotFound         = errors.New("resource not found")
+	ErrInvalidInput     = errors.New("invalid input")
+	ErrInternalServer   = errors.New("internal server error")
+	ErrUnauthorized     = errors.New("unauthorized")
+	ErrForbidden        = errors.New("forbidden")
+	ErrConflict         = errors.New("conflict")
+	ErrBadRequest       = errors.New("bad request")
+	ErrTimeout          = errors.New("timeout")
+	ErrServiceUnavailable = errors.New("service unavailable")
+)
+
+// AppError 应用错误结构
+type AppError struct {
+	Err     error
+	Message string
+	Code    int
+}
+
+func (e *AppError) Error() string {
+	if e.Message != "" {
+		return e.Message
+	}
+	return e.Err.Error()
+}
+
+func (e *AppError) Unwrap() error {
+	return e.Err
+}
+
+// NewAppError 创建新的应用错误
+func NewAppError(err error, message string, code int) *AppError {
+	return &AppError{
+		Err:     err,
+		Message: message,
+		Code:    code,
+	}
+}
+
+// WrapError 包装错误
+func WrapError(err error, message string) error {
+	return fmt.Errorf("%s: %w", message, err)
+}
+
+// IsNotFound 检查是否为资源未找到错误
+func IsNotFound(err error) bool {
+	return errors.Is(err, ErrNotFound)
+}
+
+// IsInvalidInput 检查是否为无效输入错误
+func IsInvalidInput(err error) bool {
+	return errors.Is(err, ErrInvalidInput)
+}
+
+// IsInternalServer 检查是否为内部服务器错误
+func IsInternalServer(err error) bool {
+	return errors.Is(err, ErrInternalServer)
+}
+
+// IsUnauthorized 检查是否为未授权错误
+func IsUnauthorized(err error) bool {
+	return errors.Is(err, ErrUnauthorized)
+}
+
+// IsForbidden 检查是否为禁止访问错误
+func IsForbidden(err error) bool {
+	return errors.Is(err, ErrForbidden)
+}
+
+// IsConflict 检查是否为冲突错误
+func IsConflict(err error) bool {
+	return errors.Is(err, ErrConflict)
+}
+
+// IsBadRequest 检查是否为请求错误
+func IsBadRequest(err error) bool {
+	return errors.Is(err, ErrBadRequest)
+}
+
+// IsTimeout 检查是否为超时错误
+func IsTimeout(err error) bool {
+	return errors.Is(err, ErrTimeout)
+}
+
+// IsServiceUnavailable 检查是否为服务不可用错误
+func IsServiceUnavailable(err error) bool {
+	return errors.Is(err, ErrServiceUnavailable)
+}