feat: Add error handling for relay server response and custom error pages

This commit includes the following changes:
- Added error handling in the election views to check if the relay server responds with an error message
- Included custom error pages for different HTTP status codes (401, 402, 403, 404, 419, 429, 500, 503)
- Created a new layout for the error pages

resources/views/pages/association/election/admin/[Election:year].blade.php

@@ -134,6 +134,11 @@ $loadEvents = function () {
     $request = new Request($relaySet, $requestMessage);
     $response = $request->send();
 
+    // Check for errors in the response
+    if (isset($response[config('services.relay')][0][0]) && $response[config('services.relay')][0][0] === 'ERROR') {
+        abort(500, 'Kann keine Events laden. Nostr Relay antwortet nicht.');
+    }
+
     $this->events = collect($response[config('services.relay')])
         ->map(fn($event)
             => [