refac: allowed image types and the size limit are a domain rule checked by the use case, not by the persistence layer

internal/domain/image/imageDomain.go

@@ -3,10 +3,35 @@ package image
 import (
 	"errors"
 	"io"
+	"sort"
 	"time"
 )
 
 var ErrImageNotFound = errors.New("image not found")
+var ErrImageTypeNotAllowed = errors.New("the file must be a PNG, JPEG, WEBP, or SVG image")
+var ErrImageTooLarge = errors.New("the file exceeds the maximum upload size")
+
+const MaxImageSize int64 = 10485760
+
+var allowedContentTypes = map[string]bool{
+	"image/png":     true,
+	"image/jpeg":    true,
+	"image/webp":    true,
+	"image/svg+xml": true,
+}
+
+func IsAllowedContentType(contentType string) bool {
+	return allowedContentTypes[contentType]
+}
+
+func AllowedContentTypes() []string {
+	types := make([]string, 0, len(allowedContentTypes))
+	for contentType := range allowedContentTypes {
+		types = append(types, contentType)
+	}
+	sort.Strings(types)
+	return types
+}
 
 type ImageInput struct {
 	Content     io.Reader