fix(frontend): ensure permissions for .next build directory in Dockerfile

Dockerfile

@@ -1,4 +1,5 @@
 FROM node:20-alpine AS app-builder
+USER root
 WORKDIR /app
 ENV NEXT_TELEMETRY_DISABLED=1
 ENV NEXT_PUBLIC_API_URL=https://api.canina.ir/api
@@ -13,11 +14,13 @@ RUN if [ -n "$NPM_REGISTRY" ]; then \
 COPY frontend/application/package*.json ./
 RUN npm ci --include=dev --prefer-offline --no-audit
 COPY frontend/application ./
+RUN mkdir -p /app/.next && chmod -R 777 /app
 ARG NEXT_PUBLIC_API_URL
 ENV NEXT_PUBLIC_API_URL=$NEXT_PUBLIC_API_URL
 RUN npm run build
 
 FROM node:20-alpine AS admin-builder
+USER root
 WORKDIR /app
 ENV VITE_API_URL=https://api.canina.ir/api