Fix production auth by proxying /api to backend in remote builds.

Remote frontend nginx now forwards API requests to Django so login and registration work when the host proxy only routes to port 8080.

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend/Dockerfile.prod

@@ -16,7 +16,14 @@ RUN npm run build
 
 FROM nginx:1.27-alpine AS runtime
 
-COPY nginx.conf /etc/nginx/conf.d/default.conf
+ARG VITE_DATA_MODE=local
+COPY nginx.conf /tmp/nginx.local.conf
+COPY nginx.remote.conf /tmp/nginx.remote.conf
+RUN if [ "$VITE_DATA_MODE" = "remote" ]; then \
+      cp /tmp/nginx.remote.conf /etc/nginx/conf.d/default.conf; \
+    else \
+      cp /tmp/nginx.local.conf /etc/nginx/conf.d/default.conf; \
+    fi
 COPY --from=build /app/dist /usr/share/nginx/html
 
 EXPOSE 80