fix: update environment variables in Dockerfile and use config for host in sitemap generation

Dockerfile

@@ -4,6 +4,11 @@ WORKDIR /app
 COPY package.json package-lock.json ./
 RUN npm ci
 COPY . .
+
+ENV PORT=5000
+ENV VERCEL_PROJECT_PRODUCTION_URL=http://194.59.214.243:5000
+ENV NEXT_PUBLIC_API_BASE_URL=http://194.59.214.243:5000/api
+
 RUN npm run build
 
 # Production stage