Fix ReactOnRailsPro stub in helper specs

Fixed stub to properly mock ReactOnRailsPro.configuration method
instead of using receive_message_chain which requires the module
to already implement the configuration method.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: AbanoubGhadban

spec/dummy/spec/helpers/react_on_rails_helper_spec.rb

@@ -27,7 +27,8 @@ class PlainReactOnRailsHelper
     )
 
     # Mock Pro gem configuration and helper for immediate_hydration
-    allow(ReactOnRailsPro).to receive_message_chain(:configuration, :immediate_hydration).and_return(true)
+    pro_config = Struct.new(:immediate_hydration).new(true)
+    allow(ReactOnRailsPro).to receive(:configuration).and_return(pro_config)
     allow(ReactOnRailsPro::Helper).to receive(:enhance_component_script_data) do |args|
       if args[:render_options].immediate_hydration
         dom_id = args[:render_options].dom_id