Add minimal Node 20 Alpine Dockerfile

Dockerfile

@@ -0,0 +1,18 @@
+FROM node:20-alpine
+
+WORKDIR /app
+
+# Install production dependencies
+COPY package*.json ./
+RUN npm install --omit=dev && npm cache clean --force
+
+# Copy application code
+COPY server.js ./
+
+# Run as non-root user for security
+RUN addgroup -S app && adduser -S app -G app
+USER app
+
+EXPOSE 3012
+
+CMD ["node", "server.js"]