Add Dockerfile and docker-compose.yml for containerized Express + MongoDB setup

Dockerfile

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+FROM node:22-alpine
+
+WORKDIR /app
+
+COPY package*.json ./
+
+RUN npm install --omit=dev
+
+COPY . .
+
+EXPOSE 3000
+
+CMD ["npm", "start"]
+

docker-compose.yml

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+version: "3.8"
+
+services:
+  app:
+    build: .
+    container_name: express-library-app
+    ports:
+      - "3000:3000"
+    environment:
+      - MONGODB_URI=mongodb://mongo:27017/local_library
+      - PORT=3000
+    depends_on:
+      - mongo
+
+  mongo:
+    image: mongo:6.0
+    container_name: express-library-db
+    ports:
+      - "27017:27017"
+    volumes:
+      - mongo_data:/data/db
+
+volumes:
+  mongo_data:

dummy.txt

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+# Triggering contribution log