Document Pro changelog rename in Phase 6

Update Phase 6 checklist and CLAUDE.md to reflect that the Pro changelog
will be moved from react_on_rails_pro/CHANGELOG.md to CHANGELOG_PRO.md at
the root during Phase 6.

This makes both changelogs siblings at the root level, consistent with the
monorepo sibling structure philosophy.

Author: justin808

CLAUDE.md

@@ -180,11 +180,11 @@ cd react_on_rails_pro && bundle exec rake rbs:validate
 
 **IMPORTANT: This is a monorepo with TWO separate changelogs:**
 - **Open Source**: `/CHANGELOG.md` - for react_on_rails gem and npm package
-- **Pro**: `/react_on_rails_pro/CHANGELOG.md` - for react_on_rails_pro gem and npm packages
+- **Pro**: `/CHANGELOG_PRO.md` - for react_on_rails_pro gem and npm packages
 
 When making changes, update the **appropriate changelog(s)**:
 - Open-source features/fixes → Update `/CHANGELOG.md`
-- Pro-only features/fixes → Update `/react_on_rails_pro/CHANGELOG.md`
+- Pro-only features/fixes → Update `/CHANGELOG_PRO.md`
 - Changes affecting both → Update **BOTH** changelogs
 
 ### Changelog Guidelines
@@ -195,7 +195,7 @@ When making changes, update the **appropriate changelog(s)**:
 - **Use `/update-changelog` command** for guided changelog updates with automatic formatting
 - **Version management after releases**:
   - Open source: `bundle exec rake update_changelog`
-  - Pro: `cd react_on_rails_pro && bundle exec rake update_changelog`
+  - Pro: `bundle exec rake update_changelog CHANGELOG=CHANGELOG_PRO.md`
 - **Examples**: Run `grep -A 3 "^#### " CHANGELOG.md | head -30` to see real formatting examples
 
 ## ⚠️ FORMATTING RULES

PHASE_6_CHECKLIST.md

@@ -353,6 +353,13 @@ Most should still work, but verify paths like:
 
 ### 7.2: Handle Remaining Files
 
+- [ ] **CHANGELOG.md**: Move to root as CHANGELOG_PRO.md:
+
+  ```bash
+  # Move Pro changelog to root as sibling
+  git mv react_on_rails_pro/CHANGELOG.md CHANGELOG_PRO.md
+  ```
+
 - [ ] **README.md**: Move valuable content to root README or docs/:
 
   ```bash
@@ -440,7 +447,9 @@ Most should still work, but verify paths like:
   grep -r "react_on_rails_pro/" docs/ --include="*.md"
   ```
 
-- [ ] Update CLAUDE.md if it references old paths
+- [ ] Update CLAUDE.md:
+  - Update changelog section to reference `/CHANGELOG_PRO.md`
+  - Update any paths referencing old structure
 - [ ] Update CONTRIBUTING.md
 - [ ] Update any README files