SNMP accepts malformed remote ports #25137

Description

The following code:

<?php

new SNMP(SNMP::VERSION_1, '127.0.0.1:not-a-port', 'public');
new SNMP(SNMP::VERSION_1, '127.0.0.1:123junk', 'public');

does not throw an exception. The first port is interpreted as 0, and the
second is interpreted as 123.

I expected both malformed ports to result in a ValueError. The parser should
require at least one decimal digit, reject trailing characters, and enforce the
existing 0..65535 range.

PHP Version

PHP 8.4.28-dev (cli) (built: Nov  1 2026 11:27:04) (ZTS DEBUG)
Copyright (c) The PHP Group
Zend Engine v4.4.28-dev, Copyright (c) Zend Technologies

The same permissive atoi() parsing is present on the current master branch.

Operating System

macOS 27.2 arm64