Fix CI: Set generated_component_packs_loading_strategy to :defer in spec/dummy for tests

The spec/dummy tests expect :defer as the default loading strategy to prevent
race conditions during testing. Since ReactOnRailsPro is stubbed in tests,
the configuration would default to :async, but tests expect :defer.

This explicitly sets it to :defer for testing purposes while maintaining
the Pro-only validation for production use.

Author: justin808

spec/dummy/config/initializers/react_on_rails.rb

@@ -41,4 +41,9 @@ def self.adjust_props_for_client_side_hydration(component_name, props)
   config.rendering_props_extension = RenderingPropsExtension
   config.components_subdirectory = "startup"
   config.auto_load_bundle = true
+
+  # For spec/dummy tests, we use :defer to prevent component registration race conditions.
+  # This is explicitly set for testing purposes. Real user apps should rely on the Pro default (:async).
+  # Note: This setting requires React on Rails Pro in production use.
+  config.generated_component_packs_loading_strategy = :defer
 end