🛠️ Add support for nullable recurrence interval in API and tests:

- 🗃️ Updated `meetup_events` table to allow `recurrence_interval` as nullable (default: 1).
- ✅ Added test to verify single event creation with explicit null recurrence fields.

database/migrations/2026_07_01_073725_make_recurrence_interval_nullable_on_meetup_events_table.php

@@ -0,0 +1,28 @@
+<?php
+
+use Illuminate\Database\Migrations\Migration;
+use Illuminate\Database\Schema\Blueprint;
+use Illuminate\Support\Facades\Schema;
+
+return new class extends Migration
+{
+    /**
+     * Run the migrations.
+     */
+    public function up(): void
+    {
+        Schema::table('meetup_events', function (Blueprint $table) {
+            $table->unsignedInteger('recurrence_interval')->nullable()->default(1)->change();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('meetup_events', function (Blueprint $table) {
+            $table->unsignedInteger('recurrence_interval')->default(1)->change();
+        });
+    }
+};