Add 'RUN --mount=type=cache,target=/pnpm-store' to all 3 pnpm install stages (builder/pwa-builder/production) with --store-dir /pnpm-store, plus the '# syntax=docker/dockerfile:1' directive. Set DOCKER_BUILDKIT=1 on the publish build step so the legacy builder can't break on the mount syntax. sharing=locked because builder and pwa-builder run in parallel. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>