fix: switch to nginx for static export serving (fixes 502)

Dockerfile

@@ -1,15 +1,11 @@
-FROM node:18-alpine
+FROM nginx:alpine
 
-WORKDIR /app
+# Copy custom nginx config
+COPY nginx.conf /etc/nginx/nginx.conf
 
-# Next.js standalone config and environment
-ENV NODE_ENV production
-ENV PORT 80
-ENV HOSTNAME "0.0.0.0"
-
-# Copy the pre-built standalone app from the build context
-COPY build /app
+# Copy the static export to nginx html directory
+COPY build /usr/share/nginx/html
 
 EXPOSE 80
 
-CMD ["node", "server.js"]
+CMD ["nginx", "-g", "daemon off;"]