Add Docker-based production deployment

- Multi-stage Dockerfile with Node builder and nginx server
- Nginx configuration with gzip, security headers, and caching
- Docker Compose setup with health checks
- Updated README with deployment instructions

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

.dockerignore

@@ -0,0 +1,34 @@
+# Dependencies
+node_modules
+npm-debug.log*
+
+# Build output
+dist
+
+# Git
+.git
+.gitignore
+
+# IDE
+.vscode
+.idea
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# Environment
+.env
+.env.local
+
+# Docker
+Dockerfile
+docker-compose.yml
+.dockerignore
+
+# Documentation
+README.md
+
+# Misc
+*.log
+.cache