refactor: remove deprecated next() method

The backward-compatible next() method is no longer needed since all
call sites have been updated to use the clearer method names:
- completeDeployment()
- failDeployment()
- transitionToStatus()

This completes the refactoring to make status transitions more explicit
and maintainable.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/Jobs/ApplicationDeploymentJob.php

@@ -3764,14 +3764,6 @@ COPY ./nginx.conf /etc/nginx/conf.d/default.conf");
         $this->transitionToStatus(ApplicationDeploymentStatus::FAILED);
     }
 
-    /**
-     * @deprecated Use transitionToStatus(), completeDeployment(), or failDeployment() instead.
-     */
-    private function next(string $status): void
-    {
-        $this->transitionToStatus(ApplicationDeploymentStatus::from($status));
-    }
-
     public function failed(Throwable $exception): void
     {
         $this->failDeployment();