fix: nginx reverse proxy for API/wizard, fix Object.entries null crash

- Replace serve with nginx for proper reverse proxy
- /api/* proxied to backend:8000, /wizard/* proxied to wizard:8080
- Eliminates CORS issues (same-origin requests)
- Fixes SPA fallback returning 200 for API routes (was hiding backend-down state)
- Add null guards on Object.entries for dashboard stats
- Remove VITE_API_BASE/VITE_WIZARD_PORT build args (no longer needed)

Dockerfile

@@ -4,16 +4,12 @@ WORKDIR /app
 COPY package.json package-lock.json* ./
 RUN npm install
 COPY . .
-ARG VITE_API_BASE=/api
-ARG VITE_WIZARD_PORT=18080
-ENV VITE_API_BASE=$VITE_API_BASE
-ENV VITE_WIZARD_PORT=$VITE_WIZARD_PORT
+# API and wizard are proxied via nginx — no VITE_ env vars needed
 RUN npm run build
 
-# Production stage — lightweight static server, no nginx
-FROM node:20-alpine
-RUN npm install -g serve@14
-WORKDIR /app
-COPY --from=build /app/dist ./dist
+# Production stage — nginx with reverse proxy
+FROM nginx:alpine
+COPY --from=build /app/dist /usr/share/nginx/html
+COPY nginx.conf /etc/nginx/conf.d/default.conf
 EXPOSE 3000
-CMD ["serve", "-s", "dist", "-l", "3000"]
+CMD ["nginx", "-g", "daemon off;"]