feat(docker): fail at start when AUTH_HOST or API_HOST is unset

An empty host gives a CSP connect-src that blocks every API call.
The new entrypoint check stops the container early with a clear error.

Dockerfile

@@ -12,8 +12,7 @@ RUN npm run build
 # Serve the static files using a lightweight web server
 FROM nginx:alpine
 COPY --from=builder /app/dist /usr/share/nginx/html
-# nginx.conf is a template. An env var that is not set stays in it as ${...}, and nginx then fails to start.
-ENV AUTH_HOST="" API_HOST=""
+COPY --chmod=0755 docker-entrypoint.d/10-require-hosts.sh /docker-entrypoint.d/
 COPY nginx.conf /etc/nginx/templates/default.conf.template
 EXPOSE 80
 CMD ["nginx", "-g", "daemon off;"]