command: hard wrap help message flags

This greatly improves readability when lots of flags are registered.

Signed-off-by: Ophestra <cat@gensokyo.uk>

command/flag.go

@@ -16,7 +16,13 @@ func (e FlagError) Is(target error) bool {
 }
 
 func (n *node) Flag(p any, name string, value FlagDefiner, usage string) Node {
-	value.Define(&n.suffix, n.set, p, name, usage)
+	var buf strings.Builder
+	value.Define(&buf, n.set, p, name, usage)
+	s := buf.String()
+	if len(s) > 0 && s[0] == ' ' {
+		s = s[1:]
+	}
+	n.suffix = append(n.suffix, s)
 	return n
 }