fix: set BuildKit worker networkMode=host for dashboard build

The BuildKit sandbox cannot resolve registry.npmjs.org DNS. Setting
networkMode=host in the worker config forces all RUN steps to use
the host network stack, which has confirmed internet access.

frontend/Dockerfile

@@ -4,7 +4,7 @@
 FROM registry.celestium.life/dockerhub-cache/library/node:24-alpine AS build
 WORKDIR /app
 COPY package.json package-lock.json ./
-RUN --network=host npm ci
+RUN npm ci
 COPY . .
 ARG VITE_QUERY_API_URL=""
 ARG VITE_SYMBOL_REGISTRY_URL=""