fix(ci): Dockerfile uses correct filter name lux-docs

Previous builds failed: pnpm --filter docs matched nothing.
Package name is lux-docs. Docker build tested locally — 353 pages,
/dex /cex /hsm all serve 200 from nginx container.

Dockerfile

@@ -5,7 +5,7 @@ COPY package.json pnpm-lock.yaml pnpm-workspace.yaml turbo.json ./
 COPY apps/docs/package.json apps/docs/package.json
 RUN pnpm install --frozen-lockfile
 COPY apps/docs apps/docs
-RUN pnpm --filter docs build
+RUN pnpm --filter lux-docs build
 
 FROM nginx:alpine
 COPY --from=build /app/apps/docs/out /usr/share/nginx/html