Fix port conflicts when running multiple NativePHP apps on Windows

[gwleuverink]

Multiple NativePHP applications cannot run simultaneously on Windows due to port binding conflicts. The second app fails with exit code 4294967294 (EADDRINUSE) and net::ERR_NAME_NOT_RESOLVED errors.

See issue NativePHP/laravel#651

getPort sometimes reports ports as available when they're actually bound by another process. This happens due to Windows-specific port detection issues, including TIME_WAIT states and reserved port ranges that get-port doesn't properly detect.

Proposed fix

Enhanced getPhpPort() to validate that suggested ports are actually bindable:

1. Fast path: Try get-port first (works in 99% of cases)
2. Validation: Test binding to the suggested port with a real TCP server
3. Smart fallback: If validation fails, incrementally search from suggestedPort + 1 upward

[gwleuverink]

@NativePHP/contributors What do you guys think about this?

It's not the most elegant approach, but I think it's pretty solid & will handle the 1% scenario where getPort isn't working as expected