fix: expose PORT env variable if supplied

Author: abubkr-hago

Dockerfile

@@ -1,6 +1,7 @@
 # latest supported node version when this Dockerfile was written
 ARG NODE_VERSION=22.12.0-alpine
 ARG APP_DIR=/usr/src/parse
+ARG PORT=1337
 
 # Builder stage
 FROM node:${NODE_VERSION} AS builder
@@ -26,6 +27,6 @@ COPY --from=builder ${APP_DIR}/public ./public
 
 VOLUME ["${APP_DIR}/cloud", "${APP_DIR}/logs"]
 
-EXPOSE 1337
+EXPOSE ${PORT}
 
 CMD ["node", "index.js"]