feat(API): media field type

internal/domain/entry/entryDomain.go

@@ -59,6 +59,10 @@ func invalidField(key string, rule string) error {
 	return FieldError{Key: key, Rule: rule, Cause: ErrInvalidEntry}
 }
 
+func InvalidField(key string, rule string) error {
+	return invalidField(key, rule)
+}
+
 func UniqueViolation(key string) error {
 	return FieldError{Key: key, Rule: RuleUnique, Cause: ErrUniqueViolation}
 }