feat(infra): add Docker setup for backend service

This commit introduces the initial infrastructure for the HR platform, as defined by the responsibilities of Agent 1. It includes:

- A `Dockerfile` for building the Node.js application container.
- A `docker-compose.yml` file to orchestrate the `api` and `db` services.
- An `.env.example` file to define the required environment variables.
- A `.gitignore` file to exclude unnecessary files from version control.
- A log file in `docs/agents/agent-01-infraestructura.md` to document the changes.

docker-compose.yml

@@ -0,0 +1,34 @@
+version: '3.8'
+
+services:
+  api:
+    build: .
+    ports:
+      - "3011:3011"
+    volumes:
+      - .:/usr/src/app
+    networks:
+      - app-network
+    env_file:
+      - .env
+
+  db:
+    image: postgres:13
+    restart: always
+    environment:
+      POSTGRES_USER: ${DB_USER}
+      POSTGRES_PASSWORD: ${DB_PASSWORD}
+      POSTGRES_DB: ${DB_NAME}
+    ports:
+      - "5432:5432"
+    volumes:
+      - postgres-data:/var/lib/postgresql/data
+    networks:
+      - app-network
+
+networks:
+  app-network:
+    driver: bridge
+
+volumes:
+  postgres-data: