Defensive — keeps node_modules/dist/.vite/.env out of the build context
when running `docker build` locally. Portainer's Stacks→Repository flow
clones from git (which already excludes these via .gitignore), so this
doesn't change Portainer behavior, just hardens local-docker-build paths.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
