Tell harness stateless run

<?php
require 'examples/boot.php';
require_once dirname(__DIR__).'/Support.php';

use Cognesy\Tell\Tell;
use Cognesy\Tell\TellRequest;

$project = TellHarnessExample::project();

try {
    $result = Tell::open($project)->run(
        TellRequest::prompt('In one sentence, explain why stateless jobs are useful.'),
    );

    echo "=== Tell Result ===\n";
    echo 'Completed: '.($result->isCompleted() ? 'yes' : 'no')."\n";
    echo 'Durable: '.($result->isDurable() ? 'yes' : 'no')."\n";
    echo 'Response: '.$result->text()."\n";

    assert($result->isCompleted(), 'Expected a completed Tell result.');
    assert(
        ! $result->isDurable(),
        'Stateless Tell execution must not publish history.',
    );
    assert(
        ! is_dir($project.'/.tell'),
        'Stateless Tell execution must not create a workspace.',
    );
} finally {
    TellHarnessExample::remove($project);
}