fix(intl): allow partial override of existing translations

Author: innocenzi

packages/intl/src/Catalog/CatalogInitializer.php

@@ -32,8 +32,8 @@ public function initialize(Container $container): Catalog
                     Str\ends_with($path, ['.yaml', '.yml']) => Yaml::parse($contents),
                 };
 
-                foreach (Arr\undot($messages) as $key => $message) {
-                    $catalog[$locale][$key] = $message;
+                foreach (Arr\dot($messages) as $key => $message) {
+                    $catalog[$locale] = Arr\set_by_key($catalog[$locale], $key, $message);
                 }
             }
         }