Run SuperClaude install in background

- Split SuperClaude installation into two steps
- Run 'SuperClaude install' in background to avoid blocking startup
- Allows container to start faster while setup completes

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

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

entrypoint.sh

@@ -56,7 +56,8 @@ set -e
 su - $XWINDOW_USER -c "rm -rf ~/.config/chromium/"   
 
 # install super-claude
-su - $XWINDOW_USER -c "pipx install SuperClaude && pipx upgrade SuperClaude && SuperClaude install"
+su - $XWINDOW_USER -c "pipx install SuperClaude && pipx upgrade SuperClaude"
+su - $XWINDOW_USER -c "SuperClaude install" &
 
 # start code-server in background
 su - $XWINDOW_USER -c "code-server --bind-addr 0.0.0.0:30145 --auth password /mnt" &