The committed dist was stale (older build without email-resolving + username login).
Rebuild locally and commit the fresh SPA so EasyPanel serves the correct login/setup
flow. Verified fresh dist references username/must_setup/setup.
The Vue SPA is now built locally and its frontend/dist/ committed (force-added).
Dockerfile is a single-stage runtime: copy prebuilt dist + python:3.11 + Flask.
No node/npm inside the image -> deterministic, no npm/esbuild postinstall flakiness.
To update UI: edit src, npm run build, commit frontend/dist/.