add all validator, simplify error messages

all.go

@@ -0,0 +1,14 @@
+package validate
+
+// All validates a value using a sequence of validation functions.
+// If any validation function returns an error, the sequence stops and the error is returned.
+func All[T any](fs ...func(T) error) func(T) error {
+	return func(value T) error {
+		for _, f := range fs {
+			if err := f(value); err != nil {
+				return err
+			}
+		}
+		return nil
+	}
+}