[php-src] Issue #21700: Assertion failure `_php_stream_seek` at streams/streams.c

Issue: https://github.com/php/php-src/issues/21700
Author: YuanchengJiang

### Description

The following code:

```php
<?php
class mystream {
function stream_open($path, $mode, $options, &$opened_path) { return true; }
function stream_seek($offset, $whence) {
$this->pos = $offset; // SEEK_CUR with negative offset → negative pos
return true;
}
function stream_tell() { return $this->pos; }
}
stream_wrapper_register("test", "mystream");
$fp = fopen("test://foo", "rb");
fseek($fp, -1, SEEK_CUR);
fseek($fp, 0, SEEK_CUR);
```

Resulted in this output:
```
php: /home/phpfuzz/WorkSpace/flowfusion/php-src/main/streams/streams.c:1465: int _php_stream_seek(php_stream *, zend_off_t, int): Assertion `stream->position >= 0' failed.
Aborted (core dumped)
```

To reproduce:
```
./php-src/sapi/cli/php  ./test.php
```

Commit:
```
cdc0366bbb366934e91b5461d524226ecb26c891
```

Configurations:
```
CC="clang-12" CXX="clang++-12" CFLAGS="-DZEND_VERIFY_TYPE_INFERENCE" CXXFLAGS="-DZEND_VERIFY_TYPE_INFERENCE" ./configure --enable-debug --enable-address-sanitizer --enable-undefined-sanitizer --enable-re2c-cgoto --enable-fpm --enable-litespeed --enable-phpdbg-debug --enable-zts --enable-bcmath --enable-calendar --enable-dba --enable-dl-test --enable-exif --enable-ftp --enable-gd --enable-gd-jis-conv --enable-mbstring --enable-pcntl --enable-shmop --enable-soap --enable-sockets --enable-sysvmsg --enable-zend-test --with-zlib --with-bz2 --with-curl --with-enchant --with-gettext --with-gmp --with-mhash --with-ldap --with-libedit --with-readline --with-snmp --with-sodium --with-xsl --with-zip --with-mysqli --with-pdo-mysql --with-pdo-pgsql --with-pgsql --with-sqlite3 --with-pdo-sqlite --with-webp --with-jpeg --with-freetype --enable-sigchild --with-readline --with-pcre-jit --with-iconv
```

Operating System:
```
Ubuntu 20.04 Host, Docker 0599jiangyc/flowfusion:latest
```

*This report is automatically generated by [FlowFusion](https://github.com/php/flowfusion)*

### PHP Version

```plain
nightly
```

### Operating System

_No response_