2.0.1: Publish one version string, not two (#15)
The release tag is both the Docker Hub tag and the version the UI footer
shows, so the two have to agree. Releases are tagged v2.1.0 by convention,
but 2.0 is already on Docker Hub unprefixed — publishing both forms leaves
anyone pinning FACTION_VERSION guessing which one their release used.
Strip the leading v once, where the tag is computed, so it reaches the
registry and APP_VERSION in the same form the footer already renders.
Also point the Dockerfile's comment at release.yml; release-deploy.yml is
not a file in this repository.