Tell harness branch workflow

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

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

$project = TellHarnessExample::project();

try {
    $tell = Tell::testing($project, 'deterministic workspace result');
    $workspace = $tell->workspace();
    $workspace->initialize();

    // Give main a durable head, then fork a review branch from it.
    $tell->run(TellRequest::prompt('Record the release baseline.')->durable());
    $branches = $workspace->branches();
    $review = $branches->create('release-review');
    $branches->checkout($review->name);

    $result = $tell->run(
        TellRequest::prompt('Review the release candidate.')->durable(),
    );
    echo 'Published on branch: '.$result->branch()."\n";

    // A branch handle reads that named branch regardless of later checkout.
    // Pinning captures an immutable head that remains readable after ref moves.
    $reviewHandle = $workspace->branch('release-review');
    $frozen = $reviewHandle->pin();

    // Preserve a named recovery point before moving release-review back.
    $recovery = $branches->create('release-review-recovery', from: 'release-review');
    $reset = $branches->reset('release-review', steps: 1);

    echo 'Recovery branch: '.$recovery->name."\n";
    echo 'Reset '.($reset->changed ? 'completed' : 'did not change the head')."\n";
    echo 'Review turns after reset: '.count($reviewHandle->history()->turns)."\n";
    echo 'Frozen turns: '.count($frozen->history()->turns)."\n";

    assert($result->isCompleted(), 'Expected durable branch work to complete.');
    assert($reset->changed, 'Expected the branch reset to move one ancestor back.');
    assert(count($reviewHandle->history()->turns) === 1);
    assert(count($frozen->history()->turns) === 2);
} finally {
    TellHarnessExample::remove($project);
}