Laravel 12.51.0 Adds afterSending Callbacks, Validator whenFails, and MySQL Timeout

Laravel 12.51.0 introduces notification afterSending callbacks for post-send logic, fluent whenFails and whenPasses validator methods for non-HTTP contexts, and a MySQL-specific query timeout method. The release adds closure support in firstOrCreate and createOrFirst for lazy evaluation of expensive operations, a BatchCancelled event for monitoring batch job cancellations, and the ability to use Eloquent builders directly as subqueries in updates. Additional improvements include a withoutHeader response method, enhanced batch testing assertions, cache isolation for parallel tests, and numerous bug fixes across database operations, string helpers, queue middleware, and framework internals.