fix(queue): route cloud jobs to dedicated queues

Use config-based queue selection for deployment and scheduled jobs so cloud dispatches deployments to `deployments` and scheduled jobs to `crons`, while self-hosted keeps using `high`.

Add coverage for deployment queue helper, start action routing, and scheduled job manager routing.

app/Jobs/ApplicationDeploymentJob.php

@@ -197,7 +197,7 @@ class ApplicationDeploymentJob implements ShouldBeEncrypted, ShouldQueue
 
     public function __construct(public int $application_deployment_queue_id)
     {
-        $this->onQueue('high');
+        $this->onQueue(deployment_queue());
 
         $this->application_deployment_queue = ApplicationDeploymentQueue::find($this->application_deployment_queue_id);
         $this->nixpacks_plan_json = collect([]);

app/Jobs/ScheduledJobManager.php

@@ -40,14 +40,15 @@ class ScheduledJobManager implements ShouldQueue
         $this->onQueue($this->determineQueue());
     }
 
+    /**
+     * On cloud this job runs on a dedicated `crons` queue so it can be drained by an isolated
+     * Horizon worker pool; self-hosted keeps it on the shared `high` queue. Routing is decided
+     * by `isCloud()` (config-based), so the dispatching process needs no special env — only
+     * the worker must be configured to drain `crons` via `HORIZON_QUEUES`.
+     */
     private function determineQueue(): string
     {
-        $preferredQueue = 'crons';
-        $fallbackQueue = 'high';
-
-        $configuredQueues = explode(',', env('HORIZON_QUEUES', 'high,default'));
-
-        return in_array($preferredQueue, $configuredQueues) ? $preferredQueue : $fallbackQueue;
+        return isCloud() ? 'crons' : 'high';
     }
 
     /**