getBasePath() auto-detection incorrectly strips URI segments when using PHP built-in server

[lelandyang]

Describe the bug

Router::getBasePath() auto-detects the base path using $_SERVER['SCRIPT_NAME']:

static::$serverBasePath = implode('/', array_slice(explode('/', $_SERVER['SCRIPT_NAME']), 0, -1)) . '/';

When using the PHP built-in server (php -S), $_SERVER['SCRIPT_NAME'] does not
reliably resolve to /. Instead it computes a non-root base path (e.g. /api/v1/users/)
and silently strips that prefix from every incoming request URI before route matching.

This causes all routes with path prefixes (e.g. /api/v1/users/login) to return 404,
while only the stripped suffix (e.g. /login) matches — making the bug extremely
difficult to diagnose.

To Reproduce

1. Create a Leaf MVC project
2. Define routes with prefixes in app/routes/_app.php:

app()->post('/api/v1/users/register', 'AuthController@register');
app()->get('/api/v1/users/login', 'AuthController@login');

3. Serve using PHP built-in server: php -S localhost:5500 -t public public/index.php
4. Visit http://localhost:5500/api/v1/users/login

Expected behavior

http://localhost:5500/api/v1/users/login matches the defined route and returns 200.

Actual behavior

http://localhost:5500/api/v1/users/login returns 404. Only
http://localhost:5500/login matches.

Workaround

Manually force the base path at the top of app/routes/_app.php:

app()->setBasePath('/');

Environment

• leafs/leaf version: v4.4
• leafs/mvc-core version: v4.8
• PHP SAPI: cli-server (PHP built-in server)
• OS: Linux

Suggested Fix

Default $serverBasePath to '/' instead of auto-detecting from
$_SERVER['SCRIPT_NAME'], or validate the detected value before applying it.