Add missing validation call for concurrent_component_streaming_buffer_size

Wire up validate_concurrent_component_streaming_buffer_size in
setup_config_values to ensure config.concurrent_component_streaming_buffer_size
is validated at initialization time. Without this call, invalid values
(nil, 0, negative numbers) would be silently accepted and cause runtime
errors later when Async::LimitedQueue is instantiated.

Addresses CodeRabbit feedback on the original PR.

Author: ihabadham

react_on_rails_pro/lib/react_on_rails_pro/configuration.rb

@@ -118,6 +118,7 @@ def setup_config_values
       validate_remote_bundle_cache_adapter
       setup_renderer_password
       setup_assets_to_copy
+      validate_concurrent_component_streaming_buffer_size
       setup_execjs_profiler_if_needed
       check_react_on_rails_support_for_rsc
     end