Add comprehensive --rsc-pro generator tests (#3098)

## Summary
- Add missing test assertions for the `--rsc-pro` generator context to
match the thoroughness of the `--rsc` tests
- Verifies node-renderer.js creation, RSC bundle watcher in
Procfile.dev, HelloServer replacing HelloWorld (controller + routes +
components), hello_server and rsc_payload routes, and
rscWebpackConfig.js

The `--rsc-pro` generator mode implementation was completed in #2822,
but the test coverage was incomplete — only version pinning and
DEFAULT_ROUTE were verified. This closes the gap by adding route,
component, Procfile, and webpack config assertions.

Closes #2793

## Test plan
- [x] `bundle exec rspec
react_on_rails/spec/react_on_rails/generators/install_generator_spec.rb
-e "with --rsc-pro"` — 12 examples, 0 failures
- [x] `bundle exec rubocop` — no offenses

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

<!-- CURSOR_SUMMARY -->
---

> [!NOTE]
> **Low Risk**
> Low risk: only adds RSpec assertions around generator output, with no
production code changes. Main risk is increased test brittleness if
templates evolve.
> 
> **Overview**
> Strengthens test coverage for the `react_on_rails:install --rsc-pro`
path by asserting generation of `client/node-renderer.js`, the RSC
bundle watcher entry in `Procfile.dev`, and the switch from `HelloWorld`
scaffolding to `HelloServer`.
> 
> Adds checks that `config/routes.rb` includes both `hello_server` and
`rsc_payload`, and verifies RSC-specific webpack artifacts
(`config/webpack/rscWebpackConfig.js` plus `RSCWebpackPlugin` usage and
the `rscBundle` parameter in `serverWebpackConfig`).
> 
> <sup>Reviewed by [Cursor Bugbot](https://cursor.com/bugbot) for commit
1b5b1d1. Bugbot is set up for automated
code reviews on this repo. Configure
[here](https://www.cursor.com/dashboard/bugbot).</sup>
<!-- /CURSOR_SUMMARY -->

<!-- This is an auto-generated comment: release notes by coderabbit.ai
-->
## Summary by CodeRabbit

* **Tests**
* Expanded test coverage for installation configuration validation,
including scaffold setup and configuration file generation checks.
<!-- end of auto-generated comment: release notes by coderabbit.ai -->

---------

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

@@ -1732,6 +1732,65 @@ class ActiveSupport::TestCase
       end
     end
 
+    it "creates node-renderer.js" do
+      assert_file "client/node-renderer.js" do |content|
+        expect(content).to include("reactOnRailsProNodeRenderer")
+        expect(content).to include("require('react-on-rails-pro-node-renderer')")
+      end
+    end
+
+    it "adds RSC bundle watcher to Procfile.dev" do
+      assert_file "Procfile.dev" do |content|
+        expect(content).to include("RSC_BUNDLE_ONLY=true")
+        expect(content).to include("rsc-bundle:")
+        expect(content).to include("bin/shakapacker-watch --watch")
+      end
+    end
+
+    it "creates HelloServer instead of HelloWorld" do
+      assert_no_file "app/javascript/src/HelloWorld/ror_components/HelloWorld.client.jsx"
+      assert_no_file "app/javascript/src/HelloWorld/ror_components/HelloWorld.server.jsx"
+      assert_no_file "app/controllers/hello_world_controller.rb"
+      assert_file "config/routes.rb" do |content|
+        expect(content).not_to include("hello_world")
+      end
+
+      assert_file "app/javascript/src/HelloServer/ror_components/HelloServer.jsx"
+      assert_file "app/javascript/src/HelloServer/components/HelloServer.jsx"
+      assert_file "app/javascript/src/HelloServer/components/LikeButton.jsx"
+    end
+
+    it "adds HelloServer route and RSC payload route" do
+      assert_file "config/routes.rb" do |content|
+        expect(content).to include("hello_server")
+        expect(content).to include("rsc_payload")
+      end
+    end
+
+    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
+    end
+
+    it "serverWebpackConfig includes RSCWebpackPlugin import" do
+      assert_file "config/webpack/serverWebpackConfig.js" do |content|
+        expect(content).to include("RSCWebpackPlugin")
+        expect(content).to include("react-on-rails-rsc/WebpackPlugin")
+      end
+    end
+
+    it "serverWebpackConfig has rscBundle parameter" do
+      assert_file "config/webpack/serverWebpackConfig.js" do |content|
+        expect(content).to match(/configureServer\s*=\s*\(rscBundle\s*=\s*false\)/)
+        expect(content).to include("if (!rscBundle)")
+      end
+    end
+
     it "sets DEFAULT_ROUTE to hello_server in bin/dev" do
       assert_file "bin/dev" do |content|
         expect(content).to include('DEFAULT_ROUTE = "hello_server"')