Bump version to 2.8.0 for julik-frontend-races-reviewer agent

- Add CHANGELOG entry for new frontend race condition reviewer
- Update agent count from 23 to 24 in plugin.json and marketplace.json

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

Co-Authored-By: Claude <noreply@anthropic.com>

.claude-plugin/marketplace.json

@@ -11,8 +11,8 @@
   "plugins": [
     {
       "name": "compounding-engineering",
-      "description": "AI-powered development tools that get smarter with every use. Make each unit of engineering work easier than the last. Includes 23 specialized agents, 16 commands, and 11 skills.",
-      "version": "2.6.0",
+      "description": "AI-powered development tools that get smarter with every use. Make each unit of engineering work easier than the last. Includes 24 specialized agents, 16 commands, and 11 skills.",
+      "version": "2.8.0",
       "author": {
         "name": "Kieran Klaassen",
         "url": "https://github.com/kieranklaassen",