feat(subscription): implement effective plan logic and update free plan features

src/Subscription/Entity/SubscriptionPlan.php

@@ -90,10 +90,10 @@ class SubscriptionPlan
         ];
 
         if ($withPeriods) {
-            $data['periods'] = array_map(
+            $data['periods'] = array_values(array_map(
                 fn(SubscriptionPeriod $p) => $p->toArray(),
                 $this->periods->filter(fn(SubscriptionPeriod $p) => $p->isActive())->toArray()
-            );
+            ));
         }
 
         return $data;