feat: migrate UX tools to a formal Extension (ux-toolkit)

README.md

@@ -115,14 +115,16 @@ npm install -g @google/gemini-cli@nightly
 
 ### Automation & Integration
 
-- **Custom Development Skills**: This branch introduces specialized skills for
-  the AI DevTools UX team:
+- **UX Toolkit Extension**: This branch introduces a formal extension for the AI
+  DevTools UX team. Install it to enable specialized workflows: \`gemini
+  extensions install ./packages/extensions/ux-toolkit\`
   - **\_ux_git-worktree**: Manage Git Worktrees using the "Base Folder
     Strategy".
   - **\_ux_finish-pr**: Co-author assistant for authors to cross the finish line
     with UX polish and CI fixes.
   - **\_ux_designer**: Lead UX Designer expert to review React/Ink components
     against the v1.0 Design Principles (Density, Progressive Disclosure, State).
+  - **\_ux_help**: Show the welcome guide and documentation.
 - Automate operational tasks like querying pull requests or handling complex
   rebases
 - Use MCP servers to connect new capabilities, including