feat(node): add production-ready Node.js Dockerfile templates with pnpm

- Multi-stage build with Node.js 22 slim base
- PNPM package manager via corepack (2x faster than npm)
- Build cache mounts for fast rebuilds
- Non-root user (appuser:1000) for security
- Health check using native fetch API
- Alpine variant for size optimization (~130MB)
- Distroless variant for maximum security (~110MB)
- Comprehensive .dockerignore for clean builds
- Full documentation with framework-specific guidance

node/.dockerignore

@@ -0,0 +1,72 @@
+# =============================================================================
+# .dockerignore - Exclude files from Docker build context
+# =============================================================================
+
+# Dependencies (always reinstall in container)
+node_modules/
+.pnpm-store/
+
+# Build output (rebuilt in container)
+dist/
+build/
+.next/
+.nuxt/
+.output/
+
+# Development
+*.log
+npm-debug.log*
+pnpm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+
+# Testing
+coverage/
+.nyc_output/
+*.test.js
+*.spec.js
+__tests__/
+__mocks__/
+
+# TypeScript cache
+*.tsbuildinfo
+tsconfig.tsbuildinfo
+
+# Environment files (use runtime secrets)
+.env
+.env.*
+!.env.example
+
+# IDE / Editor
+.idea/
+.vscode/
+*.swp
+*.swo
+*~
+
+# Git
+.git/
+.gitignore
+.gitattributes
+
+# Docker
+Dockerfile*
+docker-compose*.yml
+.dockerignore
+
+# CI/CD
+.github/
+.gitlab-ci.yml
+.travis.yml
+Jenkinsfile
+
+# Documentation
+*.md
+!README.md
+docs/
+LICENSE
+
+# Misc
+.DS_Store
+Thumbs.db
+*.tmp