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>

tests/Id/SubscriptionStatusTest.php

@@ -0,0 +1,56 @@
+<?php
+
+namespace Anikeen\Id\Tests;
+
+use Anikeen\Id\Billable;
+use Anikeen\Id\Enums\SubscriptionStatus;
+use Anikeen\Id\Resources\AppSubscription;
+use Illuminate\Database\Eloquent\Model;
+use PHPUnit\Framework\Attributes\DataProvider;
+
+class SubscriptionStatusTest extends TestCase
+{
+    private const BASE = ['id' => '01JSUB', 'active' => false, 'autorenew' => true, 'cancelled' => false, 'starts_at' => null, 'cancels_at' => null, 'trial_ends_at' => null];
+
+    public static function states(): array
+    {
+        $started = ['starts_at' => '2026-10-01T00:00:00+00:00'];
+
+        return [
+            'draft' => [[], SubscriptionStatus::DRAFT, false],
+            'active' => [['active' => true, ...$started], SubscriptionStatus::ACTIVE, true],
+            'trial' => [['active' => true, 'trial_ends_at' => date(DATE_ATOM, time() + 86400), ...$started], SubscriptionStatus::TRIAL, true],
+            'trial over' => [['active' => true, 'trial_ends_at' => '2026-01-01T00:00:00+00:00', ...$started], SubscriptionStatus::ACTIVE, true],
+            'paused' => [['active' => true, 'autorenew' => false, ...$started], SubscriptionStatus::PAUSED, true],
+            'cancelling' => [['active' => true, 'cancels_at' => '2027-01-01T00:00:00+00:00', ...$started], SubscriptionStatus::CANCELLING, true],
+            'expired' => [['autorenew' => false, ...$started], SubscriptionStatus::EXPIRED, false],
+            'cancelled' => [['autorenew' => false, 'cancelled' => true, ...$started], SubscriptionStatus::CANCELLED, false],
+        ];
+    }
+
+    #[DataProvider('states')]
+    public function test_the_status_follows_the_fields(array $fields, string $status, bool $running): void
+    {
+        $data = [...self::BASE, ...$fields];
+
+        $this->respond(200, ['data' => [$data]]); // subscriptions() loads the list
+        $this->respond(200, ['data' => $data]);
+        $owner = new class extends Model {
+            use Billable;
+        };
+        $owner->anikeen_id_access_token = 'user-token';
+        $subscription = $owner->subscriptions()->find('01JSUB');
+
+        $app = new AppSubscription((object) $data);
+
+        foreach ([$subscription, $app] as $resource) {
+            $this->assertSame($status, $resource->status());
+            $this->assertSame($running, $resource->isActive());
+            $this->assertSame($status === SubscriptionStatus::DRAFT, $resource->isDraft());
+            $this->assertSame($status === SubscriptionStatus::PAUSED, $resource->isPaused());
+            $this->assertSame($status === SubscriptionStatus::CANCELLING, $resource->isCancelling());
+            $this->assertSame($status === SubscriptionStatus::EXPIRED, $resource->isExpired());
+            $this->assertSame($status === SubscriptionStatus::CANCELLED, $resource->isCancelled());
+        }
+    }
+}