[php-src] Issue #21027: strtotime() has strange interpretation of decimal weeks

Issue: https://github.com/php/php-src/issues/21027
Author: hartman

### Description

The following code:

```php
<?php
strtotime("2.37685 weeks");
```

Resulted in this output:
```
1613443020
```

The code interpreted 2.37685 weeks as 02:37 (hours) and 685 weeks. This is non logical input of course (and not GNU compliant). But this isn't a very logical interpretation of this value from a human perspective.

The parser decided to not be able to recognize weeks, then fallback to hours, interpret up to 2 decimals (compliant with hour parsing), then split the remainder and continue parsing, interpreting the rest as the input for weeks.

This has been a [known issue for Wikipedia](https://phabricator.wikimedia.org/T10554) since 2007, but was never reported upstream.

### PHP Version

```plain
PHP 8.4.16 (cli) (built: Dec 16 2025 16:03:34) (NTS)
Copyright (c) The PHP Group
Built by Homebrew
Zend Engine v4.4.16, Copyright (c) Zend Technologies
    with Xdebug v3.4.0, Copyright (c) 2002-2024, by Derick Rethans
    with Zend OPcache v8.4.16, Copyright (c), by Zend Technologies
```

### Operating System

macos