feat: demo deployment with AIUI chat, SSH key auth, Quick Start fix

- Add AIUI pre-built dist to demo/ for Portainer deployment
- Add nginx-demo.conf with Claude API proxy (envsubst for API key)
- Add docker-entrypoint.sh for runtime API key injection
- Update Dockerfile.web to include AIUI and Claude proxy
- Update docker-compose.demo.yml with ANTHROPIC_API_KEY env var
- Switch deploy script from sshpass to SSH key auth
- Fix Quick Start Goals animating before other cards (stagger 5, opacity guard)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

demo/aiui/assets/init-Gi6I4Gst.js

@@ -0,0 +1 @@
+function t(e,a){switch(arguments.length){case 0:break;case 1:this.range(e);break;default:this.range(a).domain(e);break}return this}export{t as i};