Reorganize Dockerfile: move environment variable declaration and clean up RUN commands

@@ -1,19 +1,21 @@FROM alpine:3.22RUN apk add --update --no-cache nodejs yarnENV NEXT_TELEMETRY_DISABLED=1RUN apk add --update --no-cache \      nodejs yarnRUN addgroup -S -g 1000 app && \    adduser -S -h /app -s /sbin/nologin -u 1000 -G app app && \    chown -R app:app /appWORKDIR /appCOPY package.json yarn.lock /app/RUN yarn install --frozen-lockfileCOPY . .RUN yarn next:buildRUN addgroup -S -g 1000 app && \    adduser -S -h /app -s /sbin/nologin -u 1000 -G app app && \    chown -R app:app /appUSER app:app