Tell harness persistent shell jobs

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

use Cognesy\Tell\Resource\TellResourceObservers;
use Cognesy\Tell\Resource\TellShellJobApprovals;
use Cognesy\Tell\Resource\TellResourceEvent;
use Cognesy\Tell\Resource\TellResourceHost;
use Cognesy\Tell\Shell\TellShellJobPolicy;
use Cognesy\Tell\Shell\TellShellJobRequest;

$project = TellHarnessExample::project();
$events = new ArrayObject;
$host = TellResourceHost::shellJobs(
    project: $project,
    policy: new TellShellJobPolicy(
        maxConcurrentJobs: 2,
        maxLifetimeMs: 5_000,
        maxRetainedOutputBytes: 16_384,
    ),
    approval: TellShellJobApprovals::allowAll(),
    observer: TellResourceObservers::callback(
        static fn (TellResourceEvent $event) => $events->append($event->toArray()),
    ),
)->boot();

try {
    $script = <<<'PHP'
fwrite(STDOUT, "started\n");
usleep(50_000);
fwrite(STDOUT, "finished\n");
fwrite(STDERR, "diagnostic\n");
PHP;
    $command = escapeshellarg(PHP_BINARY).' -r '.escapeshellarg($script);
    $started = $host->jobs()->start(
        TellShellJobRequest::command($command)
            ->forMilliseconds(2_000)
            ->retaining(4_096)
            ->named('example-worker'),
    );

    // The process remains host-owned after start() returns. Callers retain
    // only immutable snapshots and cursored output, never a raw process handle.
    $finished = $host->jobs()->wait($started->id, 3_000);
    $output = $host->jobs()->read($started->id);

    echo $output->text();
    echo 'State: '.$finished->state->value."\n";
    echo 'Resource events: '.count($events)."\n";

    assert($finished->isTerminal());
    assert($finished->exitCode === 0);
    assert(str_contains($output->text(), 'started'));
    assert(str_contains($output->text(), 'diagnostic'));
} finally {
    // This also cancels any still-running jobs, in reverse ownership order.
    $host->dispose();
    TellHarnessExample::remove($project);
}