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.

resources/views/columns/meetups/action.blade.php

@@ -68,6 +68,19 @@
             </x-button>
         </div>
     @endif
+    @if($row->signal)
+        <div>
+            <x-button
+                xs
+                black
+                target="_blank"
+                :href="$row->signal"
+            >
+                <i class="fa fa-thin fa-external-link mr-2"></i>
+                {{ __('Signal') }}
+            </x-button>
+        </div>
+    @endif
     @if($row->webpage)
         <div>
             <x-button