(feat) Worker: run every job in its own defer() scope

[techmahedy]

Problem

With defer() available in the framework, jobs have no execution scope of their own. A queue worker is a long-lived process, so a callback registered by one job must not survive into the next, and cleanup has to run before the worker records the job's outcome.

Solution

QueueWorker::executeJob() runs $job->handle() through app()->runInDeferScope():

public function handle(): void
{
    $lock = cache()->locked('invoice:' . $this->invoiceId, seconds: 60);

    if (! $lock->get()) {
        throw new \RuntimeException('Invoice is already being sent; the job will be retried.');
    }

    app()->defer(static fn () => $lock->release());

    $this->sendInvoice();
}

Behavior

• Each job gets its own scope. Callbacks registered by one job never reach the next.
• Callbacks run when the job finishes, after success or after an exception, before the worker deletes, releases, or fails the job.
• Works for jobs run in-process and in the timeout child process, because executeJob() is the shared point and the callbacks run in the process that ran the job.
• Jobs run through dispatchSync() / queueAsSync() / Drain execute inside the caller's execution, so their defer() callbacks belong to the caller's scope. This is unchanged.

Compatibility

The call is guarded with method_exists($app, 'runInDeferScope'), so the
worker behaves exactly as before on framework versions that do not have
defer(). No new requirement is added to composer.json.

Tests

Two tests in QueueWorkerTest, using a container that implements the scope
API:

• each job runs in its own scope and cleanup runs between jobs (run-a, cleanup-a, run-b, cleanup-b)
• cleanup runs when a job fails, before the failure is handled