all: adopt maps and cmp helpers

cmd/headscale/cli/users.go

@@ -36,9 +36,7 @@ func usernameAndIDFromFlag(cmd *cobra.Command) (uint64, string, error) {
 
 	// Normalise unset/negative identifiers to 0 so the uint64
 	// conversion does not produce a bogus large value.
-	if identifier < 0 {
-		identifier = 0
-	}
+	identifier = max(identifier, 0)
 
 	return uint64(identifier), username, nil //nolint:gosec // identifier is clamped to >= 0 above
 }