feat: tambah sistem poin anggota (kehadiran +10, artikel +5)

- Model MemberPoint + migration
- PostObserver: +5 poin saat artikel dipublish
- ActivityObserver: +10 poin saat peserta hadir di kegiatan
- MemberPointResource: tampil di grup Organisasi
- MemberPointSeeder + update ActivitySeeder dengan pivot status kehadiran
- Update PermissionSeeder: anggota bisa lihat poin

app/Observers/PostObserver.php

@@ -0,0 +1,22 @@
+<?php
+
+namespace App\Observers;
+
+use App\Models\MemberPoint;
+use App\Models\Post;
+
+class PostObserver
+{
+    public function updated(Post $post): void
+    {
+        if ($post->wasChanged('status') && $post->status === 'published') {
+            MemberPoint::create([
+                'user_id'     => $post->user_id,
+                'points'      => 5,
+                'reason'      => "Artikel dipublikasi: {$post->title}",
+                'source_type' => 'post',
+                'source_id'   => $post->id,
+            ]);
+        }
+    }
+}