Add missing rscWebpackConfig.js assertions to --rsc-pro test

Both --rsc and --rsc-pro use the same template, so the assertions
should match. Adds the 3 missing checks: require path, default
unwrap, and serverWebpackConfig(true) call.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: justin808

react_on_rails/spec/react_on_rails/generators/install_generator_spec.rb

@@ -1769,6 +1769,9 @@ class ActiveSupport::TestCase
 
     it "creates rscWebpackConfig.js" do
       assert_file "config/webpack/rscWebpackConfig.js" do |content|
+        expect(content).to include("const serverWebpackModule = require('./serverWebpackConfig')")
+        expect(content).to include("const serverWebpackConfig = serverWebpackModule.default || serverWebpackModule")
+        expect(content).to include("serverWebpackConfig(true)")
         expect(content).to include("rsc-bundle")
         expect(content).to include("react-server")
       end