refactor: cleanup debug logs and add explicit exit in error handling flow

- Remove redundant `error_log` statements in `RouterSetup`
- Comment out unused route analysis and subdomain checks
- Add `exit()` after error rendering in `ErrorKernel`

src/Framework/ExceptionHandling/ErrorKernel.php

@@ -21,6 +21,8 @@ final readonly class ErrorKernel
 
         $this->rendererFactory->getRenderer()->render();
 
+        exit();
+
         return null;
     }
 }