Fix fatal error with statemachine v3.0.0

[Metabor]

The example has not run since the v3.0.0 upgrade on 8 April: index.php dies with a fatal error before printing a single line of output.

PHP Fatal error: Declaration of Example\Order\Command\Authorize::__invoke(Order $order, ArrayAccess $context)
must be compatible with Metabor\Statemachine\Command::__invoke(mixed ...$args): void

Why

v3.0.0 changed two signatures:

Command::__invoke(mixed ...$args): void
ConditionInterface::checkCondition(object $subject, ArrayAccess $context): bool

The example classes still implement their 2015 form. PHP rejects the narrower child declarations (contravariance). The v3.0.0 upgrade (#4) touched composer.json, composer.lock and phpunit.xml.dist — no PHP file.

What changes

Authorize::__invoke	mixed ...$args): void, arguments unpacked
Authorize::__toString	: string
both Conditions	object $subject … : bool, getName(): string
Order::triggerEvent	?ArrayAccess — implicit nullable is deprecated since 8.4

The variadic signature is forced by the parent class, so the type check the old signature used to perform is gone. Authorize now guards for it in the body, the same way ShippingDateGreater14Days already does — without it, calling it with the wrong type fails later and less clearly (Call to undefined method stdClass::getNumber() instead of a named exception).

Verification

Fresh clone, PHP 8.5.4:

without this PR:  fatal error, no example output
with this PR:     all four orders run through — 9 state transitions,
                  26 status lines, 10 events (one of them intentionally rejected)

The full example runs again, including the deliberate failure at the end (Current state "payment failed" doesn't have event "returned").

Note: running the example still emits 21 deprecations per run coming from the library itself, visible under error_reporting=E_ALL — Statemachine#29 addresses those.