fix: mkdir public before COPY in Dockerfile

Dockerfile

@@ -20,6 +20,7 @@ ENV NODE_ENV=production
 ENV NEXT_TELEMETRY_DISABLED=1
 RUN addgroup --system --gid 1001 nodejs
 RUN adduser --system --uid 1001 nextjs
+RUN mkdir -p ./public
 COPY --from=builder /app/public ./public
 RUN mkdir .next
 RUN chown nextjs:nodejs .next