fix: ensure environment variables are loaded before building

Dockerfile

@@ -23,6 +23,13 @@ ENV NODE_ENV=production
 # 🔍 Optional: Log key envs for debug
 RUN echo "📄 .env.production contents:" && cat .env.production \
  && echo "🔧 Current ENV available to Next.js build:" && printenv | grep -E 'SUPABASE|STRIPE|NEXT|NODE_ENV' || true
+
+RUN set -a \
+ && . .env \
+ && . .env.production \
+ && set +a \
+ && pnpm build
+
 RUN node check-env.js
 
 RUN pnpm build