🗓️ Add MeetupEventFactory, implement rate limiting for calendar downloads, and enhance test coverage

- **Added:** `MeetupEventFactory` for generating test data.
- **Implemented:** Rate limiting (`throttle:calendar`) for `stream-calendar` routes to prevent abuse.
- **Enhanced:** `DownloadMeetupCalendar` controller with validation and cleaner query structure.
- **Added:** Feature tests for calendar downloading, invalid input handling, and rate limiting.

tests/Feature/DownloadMeetupCalendarTest.php

@@ -0,0 +1,65 @@
+<?php
+
+use App\Models\Country;
+use App\Models\Meetup;
+use App\Models\MeetupEvent;
+use function Pest\Laravel\get;
+
+it('redirects when meetup parameter contains invalid characters', function () {
+    $response = get('/stream-calendar?meetup=49)');
+
+    $response->assertRedirect();
+});
+
+it('redirects when meetup parameter is not an integer', function () {
+    $response = get('/stream-calendar?meetup=abc');
+
+    $response->assertRedirect();
+});
+
+it('returns 404 when meetup ID does not exist', function () {
+    $response = get('/stream-calendar?meetup=999999');
+
+    $response->assertStatus(404);
+});
+
+it('returns calendar for valid meetup ID', function () {
+    $country = Country::factory()->create();
+    $city = \App\Models\City::factory()->create([
+        'country_id' => $country->id,
+    ]);
+    $meetup = Meetup::factory()->create([
+        'city_id' => $city->id,
+    ]);
+    MeetupEvent::factory()->create([
+        'meetup_id' => $meetup->id,
+        'start' => now()->addDay(),
+    ]);
+
+    $response = get("/stream-calendar?meetup={$meetup->id}");
+
+    $response->assertStatus(200);
+    $response->assertHeader('Content-Type', 'text/calendar; charset=utf-8');
+});
+
+it('returns 429 when rate limit is exceeded', function () {
+    $country = Country::factory()->create();
+    $city = \App\Models\City::factory()->create([
+        'country_id' => $country->id,
+    ]);
+    $meetup = Meetup::factory()->create([
+        'city_id' => $city->id,
+    ]);
+    MeetupEvent::factory()->create([
+        'meetup_id' => $meetup->id,
+        'start' => now()->addDay(),
+    ]);
+
+    // Make 61 requests to exceed the 60 per minute limit
+    for ($i = 0; $i < 61; $i++) {
+        $response = get("/stream-calendar?meetup={$meetup->id}");
+    }
+
+    // The last request should be rate limited
+    $response->assertStatus(429);
+});