feat: add Docker development environment for frontend

Create containerized development setup for safe and consistent frontend development:

Docker Configuration:
- docker-compose.yml: Root-level orchestration with frontend service
- frontend/Dockerfile.dev: Node.js 20 Alpine optimized for dev
- Volume mounts for Hot Module Replacement (HMR)
- Named volume for node_modules to avoid conflicts
- Health check to verify service availability
- Environment variables for file watching (CHOKIDAR_USEPOLLING)

Vite Configuration Update:
- vite.config.ts: Add server config for Docker compatibility
- host: '0.0.0.0' to accept external connections
- usePolling: true for file watching in container
- port: 5173 explicitly configured

Documentation:
- README.md: Add Docker development procedure section
- Document docker compose up -d workflow
- Explain HMR and hot-reload capabilities
- List advantages of Docker-based development

Usage:
  docker compose up -d        # Start development server
  docker compose logs -f      # View logs
  docker compose down         # Stop container

Access: http://localhost:5173

Safety First:
- Isolated environment prevents system conflicts
- Reproducible setup across different machines
- No host Node.js installation required
- Easy team onboarding

Refs: Docker best practices for Node.js development

docker-compose.yml

@@ -0,0 +1,33 @@
+# Docker Compose - LogWhisperer AI Development Environment
+# Usage: docker compose up -d
+# Access: http://localhost:5173
+
+services:
+  frontend:
+    build:
+      context: ./frontend
+      dockerfile: Dockerfile.dev
+    container_name: logwhisperer-frontend-dev
+    ports:
+      - "5173:5173"
+    volumes:
+      # Mount source code for Hot Module Replacement (HMR)
+      - ./frontend:/app
+      # Use named volume for node_modules to avoid conflicts with host
+      - node_modules:/app/node_modules
+    environment:
+      - NODE_ENV=development
+      - CHOKIDAR_USEPOLLING=true
+    # Ensure container restarts on failure
+    restart: unless-stopped
+    # Health check to verify the service is running
+    healthcheck:
+      test: ["CMD", "wget", "-q", "--spider", "http://localhost:5173"]
+      interval: 30s
+      timeout: 10s
+      retries: 3
+      start_period: 40s
+
+volumes:
+  node_modules:
+    driver: local