add test-cicd code

code/sample-nodejs-app/Dockerfile

@@ -0,0 +1,16 @@
+# Build stage
+FROM node:18-slim AS builder
+WORKDIR /app
+COPY package*.json ./
+RUN npm install
+COPY . .
+
+# Production stage
+FROM node:18-slim
+WORKDIR /app
+COPY --from=builder /app/package*.json ./
+COPY --from=builder /app/node_modules ./node_modules
+COPY --from=builder /app/index.js ./
+
+EXPOSE 3000
+CMD ["node", "index.js"]