Fix WhatsApp webhook: fallback verify token from config when no DB record exists

Solves chicken-and-egg: Meta verifies webhook before credentials are saved.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/Http/Controllers/WhatsAppWebhookController.php

@@ -18,7 +18,8 @@ public function verify(Request $request): Response
         $challenge = $request->query('hub_challenge');
 
         $channel = MessagingChannel::where('name', 'whatsapp')->where('is_active', true)->first();
-        $expectedToken = $channel?->credentials['webhook_verify_token'] ?? '';
+        $expectedToken = $channel?->credentials['webhook_verify_token']
+            ?? config('services.whatsapp.webhook_verify_token', '');
 
         if ($mode === 'subscribe' && !empty($expectedToken) && $token === $expectedToken) {
             return response($challenge, 200)->header('Content-Type', 'text/plain');

config/services.php

@@ -35,4 +35,8 @@
         ],
     ],
 
+    'whatsapp' => [
+        'webhook_verify_token' => env('WHATSAPP_WEBHOOK_VERIFY_TOKEN', 'elcaptain_whatsapp_verify_2024'),
+    ],
+
 ];