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

database/migrations/2026_04_03_233440_create_member_points_table.php

@@ -0,0 +1,26 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    public function up(): void
+    {
+        Schema::create('member_points', function (Blueprint $table) {
+            $table->id();
+            $table->foreignId('user_id')->constrained('users');
+            $table->integer('points');
+            $table->string('reason');
+            $table->string('source_type')->nullable(); // activity, post
+            $table->unsignedBigInteger('source_id')->nullable();
+            $table->timestamps();
+        });
+    }
+
+    public function down(): void
+    {
+        Schema::dropIfExists('member_points');
+    }
+};