format: fix psr12 style issues

phpcbf auto-fixes: string concatenation spacing, single-line class braces, closing brace placement.

backend/app/Middleware/AuthMiddleware.php

@@ -17,7 +17,8 @@ class AuthMiddleware implements MiddlewareInterface
     public function __construct(
         private SessionRepository $sessionRepo,
         private Clock $clock,
-    ) {}
+    ) {
+    }
 
     public function process(
         ServerRequestInterface $request,