fix(frontend): copy .npmrc into docker builds, use glibc build stage

npm ci in the images ran without frontend/.npmrc, so the eslint 9/10 peer
conflict aborted it (legacy-peer-deps=true lives in .npmrc). The release
build stage also used alpine/musl, where npm ci skipped the rolldown
native bindings and vite build failed; build on glibc like dev instead.

frontend/Dockerfile.dev

@@ -1,6 +1,6 @@
 FROM node:22 AS dev
 WORKDIR /app
-COPY frontend/package.json frontend/package-lock.json ./
+COPY frontend/package.json frontend/package-lock.json frontend/.npmrc ./
 RUN npm ci
 EXPOSE 5173
 CMD ["npm", "run", "dev", "--", "--host", "0.0.0.0"]