Add Dockerfile.dev for local development with hot reload

- Dockerfile.dev: Development environment with hot reload & cache mount
- Add Makefile targets: build-dev, run-dev for easy local testing
- Hot reload watches agent, api, common directories
- Includes health check endpoint

Usage:
  make build-dev  # Build dev image
  make run-dev    # Run container with volume mount for hot reload

backend/Dockerfile.dev

+# ============================================================
+# DOCKERFILE.DEV - Local Development (Hot Reload + Cache)
+# ============================================================
+# Sử dụng Python 3.11 Slim để tối ưu dung lượng
+FROM python:3.11-slim
+
+# Thiết lập thư mục làm việc
+WORKDIR /app
+
+# Thiết lập biến môi trường
+ENV PYTHONUNBUFFERED=1
+ENV PYTHONDONTWRITEBYTECODE=1
+ENV ENV=development
+
+# Copy requirements.txt trước để tận dụng Docker cache
+COPY requirements.txt .
+
+# Cài đặt thư viện Python (với cache mount cho tốc độ)
+RUN --mount=type=cache,target=/root/.cache/pip \
+    pip install -r requirements.txt
+
+# Copy toàn bộ source code vào image
+COPY . .
+
+# Expose port 5000
+EXPOSE 5000
+
+# Health check (optional)
+HEALTHCHECK --interval=10s --timeout=5s --start-period=5s --retries=2 \
+    CMD python -c "import requests; requests.get('http://localhost:5000/docs')" || exit 1
+
+# Lệnh chạy server với hot reload
+# ⚡ Hot reload - tự động restart khi code thay đổi (cho local dev)
+CMD ["uvicorn", "server:app", "--host", "0.0.0.0", "--port", "5000", "--reload", "--reload-dirs", "agent,api,common"]

backend/Makefile

 # Makefile cho CANIFA Chatbot
 
-.PHONY: up down restart logs build ps clean setup-nginx monitor-up monitor-down
+.PHONY: up down restart logs build ps clean setup-nginx monitor-up monitor-down build-dev run-dev
 
 up:
 	sudo docker compose up -d --build
@@ -20,6 +20,12 @@ ps:
 build:
 	docker-compose build
 
+build-dev:
+	docker build -f Dockerfile.dev -t canifa-backend:dev .
+
+run-dev:
+	docker run -it --rm -v $(PWD):/app -p 5000:5000 canifa-backend:dev
+
 clean:
 	docker-compose down -v --rmi all --remove-orphans