Add subscription status helpers

status() returns draft, trial, active, paused, cancelling, expired or
cancelled (SubscriptionStatus constants), derived from the fields the
same way Anikeen ID derives its status, so it also works with older
responses. isActive() is true while the subscription runs and is paid.
Both Subscription and AppSubscription have them. Document the states.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/Id/Resources/AppSubscription.php

@@ -2,6 +2,7 @@
 
 namespace Anikeen\Id\Resources;
 
+use Anikeen\Id\Concerns\HasSubscriptionStatus;
 use Anikeen\Id\Exceptions\ApiException;
 use Anikeen\Id\Support\AppRequest;
 use DateTimeInterface;
@@ -24,7 +25,9 @@ use JsonSerializable;
  * @property bool $active
  * @property bool $autorenew
  * @property bool $cancelled
- * @property ?string $status "active" or "inactive"
+ * @property ?string $status draft, trial, active, paused, cancelling, expired or cancelled, see status()
+ * @property ?string $cancels_at when a scheduled cancellation takes effect
+ * @property ?string $trial_ends_at
  * @property ?string $starts_at
  * @property ?string $ends_at
  * @property ?string $accounting_at
@@ -36,6 +39,8 @@ use JsonSerializable;
  */
 class AppSubscription implements JsonSerializable
 {
+    use HasSubscriptionStatus;
+
     public function __construct(protected object $data)
     {
     }