feat: improved error handling in controllers, cleanup

src/Exception/BookingSessionNotFoundException.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Exception;
+
+use Symfony\Component\HttpKernel\Exception\HttpException;
+
+/**
+ * Exception thrown when attempting to access booking steps without a valid session.
+ *
+ * This exception is used when step controllers are accessed without going through
+ * the proper initialization flow or when the booking session has expired.
+ */
+class BookingSessionNotFoundException extends HttpException
+{
+    public function __construct(?\Throwable $previous = null)
+    {
+        $message = 'No valid booking session found. Please start a new booking.';
+
+        parent::__construct(404, $message, $previous);
+    }
+}