Revert "Harden frontend npm install against transient registry timeouts"

This reverts commit daa11cb768.

frontend/Dockerfile

@@ -1,5 +1,3 @@
-# syntax=docker/dockerfile:1.7
-
 FROM node:22-slim AS base
 
 ARG NPM_REGISTRY=https://registry.npmjs.org/
@@ -12,14 +10,12 @@ WORKDIR /app
 
 COPY package.json /app/package.json
 COPY package-lock.json /app/package-lock.json
-RUN --mount=type=cache,id=dcm-frontend-npm-cache,target=/root/.npm npm config set registry "${NPM_REGISTRY}" \
+RUN npm config set registry "${NPM_REGISTRY}" \
     && npm config set fetch-retries "${NPM_FETCH_RETRIES}" \
     && npm config set fetch-retry-mintimeout "${NPM_FETCH_RETRY_MINTIMEOUT}" \
     && npm config set fetch-retry-maxtimeout "${NPM_FETCH_RETRY_MAXTIMEOUT}" \
     && npm config set fetch-timeout "${NPM_FETCH_TIMEOUT}" \
-    && npm config set prefer-offline true \
-    && npm config set progress false \
-    && NODE_OPTIONS=--dns-result-order=ipv4first npm ci --no-audit --prefer-offline \
+    && NODE_OPTIONS=--dns-result-order=ipv4first npm ci --no-audit \
     && chown -R node:node /app
 
 COPY --chown=node:node tsconfig.json /app/tsconfig.json