Fix CONTRIBUTING.md and clarify workspace dependency guidance

Documentation fixes addressing Phase 6 restructuring feedback:

1. Fix Pro gem path in CONTRIBUTING.md (line 79):
   - WAS: path: "<React on Rails root>/react_on_rails_pro"
   - NOW: path: "<React on Rails root>"
   - After Phase 6, Pro gemspec is at repository root

2. Clarify workspace dependency behavior in testing-build-scripts.md:
   - Added note explaining yarn.lock behavior with "*" dependencies
   - Clarified that seeing [email protected] in yarn.lock is normal
   - Yarn still hoists workspace packages correctly despite cached version

Testing completed:
✅ gem build react_on_rails.gemspec - SUCCESS
✅ gem build react_on_rails_pro.gemspec - SUCCESS
✅ rake release[16.2.0.beta.13,true] - SUCCESS (paths all correct)

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

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

Author: justin808

.claude/docs/testing-build-scripts.md

@@ -137,9 +137,13 @@ For Yarn Classic workspaces:
 In Yarn Classic workspaces:
 
 - `"*"` tells Yarn to resolve to the local workspace package
-- Yarn automatically links to the workspace version
+- Yarn automatically hoists the workspace package to root node_modules
 - This is the official Yarn v1 workspace syntax
 
+**Note:** You may see `react-on-rails@*` with a version like `16.1.2` in yarn.lock.
+This is normal - Yarn caches the resolution, but still uses workspace hoisting at
+install time. The workspace package won't have its own node_modules subfolder.
+
 ### Testing Workspace Changes
 
 When modifying workspace dependencies in package.json:

CONTRIBUTING.md

@@ -76,7 +76,7 @@ gem "react_on_rails", path: "<React on Rails root>"
 and/or
 
 ```ruby
-gem "react_on_rails_pro", path: "<React on Rails root>/react_on_rails_pro"
+gem "react_on_rails_pro", path: "<React on Rails root>"
 ```
 
 Note that you will need to run `bundle install` after making this change, but also that **you will need to restart your Rails application if you make any changes to the gem**.