Fix webhook URL generation to include workflow slug

The Activity::webhookUrl() method was generating URLs that didn't match
the route pattern registered by Webhooks::registerSignalWebhooks(),
causing 404 errors when external services called the webhooks.

- Added workflow slug to signal webhook URL generation
- Updated test to expect the correct URL format with workflow slug

Resolves issue where signal webhooks were failing due to URL mismatch.

Author: rmcdaniel

src/Activity.php

@@ -77,12 +77,14 @@ public function workflowId()
     public function webhookUrl(string $signalMethod = ''): string
     {
         $basePath = config('workflows.webhooks_route', '/webhooks');
+        $workflow = Str::kebab(class_basename($this->storedWorkflow->class));
+
         if ($signalMethod === '') {
-            $workflow = Str::kebab(class_basename($this->storedWorkflow->class));
             return url("{$basePath}/{$workflow}");
         }
+
         $signal = Str::kebab($signalMethod);
-        return url("{$basePath}/signal/{$this->storedWorkflow->id}/{$signal}");
+        return url("{$basePath}/signal/{$workflow}/{$this->storedWorkflow->id}/{$signal}");
     }
 
     public function handle()

tests/Unit/ActivityTest.php

@@ -131,6 +131,6 @@ public function testWebhookUrl(): void
         ]);
 
         $this->assertSame('http://localhost/webhooks/test-workflow', $activity->webhookUrl());
-        $this->assertSame('http://localhost/webhooks/signal/1/other', $activity->webhookUrl('other'));
+        $this->assertSame('http://localhost/webhooks/signal/test-workflow/1/other', $activity->webhookUrl('other'));
     }
 }