We currently have a popup that shows if backend and frontend versions match:

However, this requires manual commits and we don't always bump up versions. Sometimes in debugging it is useful to know the exact dev/prod versions of frontend. I propose to add commit hashes. They could be hidden behind feature flags. The commit hash could be injected by frontend build script.

Also, the backend has a https://dev.sub.gargantext.org/api/v1.0/version endpoint, it could additional send its commit hash as well.