Add multi-stage Dockerfile and nginx configuration:
**Dockerfile**
- Stage 1: Build with Node.js 22 Alpine and pnpm 9
- Stage 2: Serve with nginx 1.27 Alpine
- Static export optimization
- Health check endpoint
**nginx.conf**
- Gzip compression for assets
- CORS headers for Canvas API
- Cache static assets (1 year)
- Don't cache HTML files
- Support for WebAssembly files
- Security headers
- Client max body size: 100M for large image uploads
Ready for containerized deployment.
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
