The install-plugins fix (209b804) only covered docker exec. build-assets
runs `docker run node:20-alpine` without --user, so it still writes
root-owned node_modules + esbuild bundles into user/themes/ — which is what
blocked `git worktree remove` at teardown. Broaden the doc and prevention
rule to cover docker run, with the --user fix.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Mpdu3Dt1iVoozHwAMyjrbn