This PR adds support for the Booking scope in the PHP SDK.

• Added the Booking scope builder and typed services for booking, waitlist, resource, resource type, resource slots, client type, booking client, booking external data, waitlist client, and waitlist external data methods.
• Added typed result DTOs for Booking entities and operation results.
• Added integration coverage for CRUD flows and dedicated annotation validation tests for Booking result items.
• Wired the new Booking tests into the PHPUnit testsuite and Makefile target.
• Updated the Booking client type contract to match the live API response shape returned by the portal.

Example usage:

$builder = ServiceBuilderFactory::createServiceBuilderFromWebhook($webhookUrl);
$bookingScope = $builder->getBookingScope();

$resourceTypeId = $bookingScope->resourceType()->add([
    'code' => 'room',
    'name' => 'Room',
])->getId();

$resourceId = $bookingScope->resource()->add([
    'typeId' => $resourceTypeId,
    'name' => 'Room A',
])->getId();

$bookingId = $bookingScope->booking()->add([
    'name' => 'Consultation',
    'resourceIds' => [$resourceId],
    'datePeriod' => [
        'from' => ['timestamp' => time() + 3600, 'timezone' => 'Europe/Berlin'],
        'to' => ['timestamp' => time() + 5400, 'timezone' => 'Europe/Berlin'],
    ],
])->getId();

$booking = $bookingScope->booking()->get($bookingId);

Quality-gate checklist

• make lint-cs-fixer
• make lint-phpstan
• make lint-rector
• make test-unit
• make test-integration-scope-booking
• docker-compose run --rm php-cli vendor/bin/phpstan analyse tests/Integration/Services/Booking

Closes #473