🚀 **Automate Meetup Activity Recalculation**

- Introduced `recalculateActivity` method in `Meetup` model to centralize activity and event timestamp updates.
- Added `MeetupEventObserver` to trigger activity recalculation on event save/delete.
- Updated `/meetups:update-activity` command to leverage the new model method for cleanup.
- Enhanced tests to cover various `MeetupEvent` scenarios affecting activity states.

app/Observers/MeetupEventObserver.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace App\Observers;
+
+use App\Models\MeetupEvent;
+
+class MeetupEventObserver
+{
+    public function saved(MeetupEvent $meetupEvent): void
+    {
+        $meetupEvent->meetup?->recalculateActivity();
+    }
+
+    public function deleted(MeetupEvent $meetupEvent): void
+    {
+        $meetupEvent->meetup?->recalculateActivity();
+    }
+}