Update Dockerfile and package.json to include environment variables, expose port, and add server entry point; add server implementation in src/server.ts with health check and greeting endpoint.

Dockerfile

@@ -6,9 +6,12 @@ COPY package.json package-lock.json* tsconfig.json ./
 RUN npm install --no-audit --progress=false
 
 COPY src ./src
+COPY .env* ./
 
 RUN npm run build && npm pack
 
-CMD ["node", "dist/index.js"]
+ENV PORT=3000
+EXPOSE 3000
+CMD ["node", "dist/server.js"]