feat(frontend): Add Docker containerization support for development and production

Implement complete Docker setup for Next.js 16 frontend with multi-stage builds,
hot reload support, and production optimizations.

Changes:
- Add Dockerfile with multi-stage build (deps, builder, development, production)
- Add .dockerignore to exclude unnecessary files from Docker context
- Add .env.local.example template for environment configuration
- Update next.config.ts with standalone output for production builds
- Add Docker convenience scripts to package.json for easy container management
- Support hot reload in development with volume mounts
- Use Node.js 20 Alpine for smaller image size
- Implement security best practices (non-root user in production)

Technical Details:
- Development stage: Full source mounted with hot reload via Turbopack
- Production stage: Standalone build with optimized static assets
- Image size: ~1.17GB (development), smaller for production
- Port: 3000 (maps to container port 3000)

Testing:
- Docker build verified for development target
- Container startup successful with Next.js 16.0.1
- HTTP 200 response confirmed on localhost:3000
- Hot reload functional with volume mounts

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

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

.dockerignore

@@ -0,0 +1,50 @@
+# Dependencies
+node_modules/
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+
+# Next.js
+.next/
+out/
+build/
+
+# Environment files
+.env
+.env*.local
+.env.production
+
+# Git
+.git/
+.gitignore
+
+# IDE
+.vscode/
+.idea/
+*.swp
+*.swo
+*~
+.DS_Store
+
+# OS files
+.DS_Store
+Thumbs.db
+
+# Testing
+coverage/
+.nyc_output/
+__tests__/
+*.test.ts
+*.test.tsx
+*.spec.ts
+*.spec.tsx
+
+# Documentation
+README.md
+*.md
+
+# Misc
+*.log
+.eslintcache
+.prettierignore