Two things in the deploy did not do what they looked like:
build-server passed --build-arg APP_VERSION, but the Dockerfile declares
ARG VERSION. An unknown build arg is ignored with a warning, so every
deployed image was stamped "dev": `keeporgd -version` and the image's
version label both said so, whatever the tag claimed.
The build pipeline's path filter listed 'VERSION', a file this repository
does not have, and '*.go', which under doublestar matches only top-level
Go files, of which there are none. So a push that changed only Go code or
only the version did not trigger a build. Now versions.mk and '**/*.go'.
Proved: built with --build-arg VERSION=0.5.0 and ran -version in the
container, which now reports 0.5.0.