feat: add signal field to meetups

- Added a new field "Signal" to the meetups form
- Included validation for the new signal field in the form backend
- Updated landing page to display the signal link if available
- Added display of the signal link in the meetup action column
- Created a new migration to add the signal field to the meetups table
- Included the signal field in the API endpoints for meetups and events.

database/migrations/2024_09_24_151929_add_signal_field_to_meetups_table.php

@@ -0,0 +1,27 @@
+<?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('meetups', function (Blueprint $table) {
+            $table->string('signal', 255 * 2)->nullable();
+        });
+    }
+
+    /**
+     * Reverse the migrations.
+     */
+    public function down(): void
+    {
+        Schema::table('meetups', function (Blueprint $table) {
+            //
+        });
+    }
+};