- add dedicated `slim` Dockerfile stage based on `full`
- move image cleanup into slim stage via slim.sh
- extend build script to support `--target slim`
- publish pkgmgr-*-slim images for all distros
https://chatgpt.com/share/69701a4e-b000-800f-be7e-162dcb93b1d2
Introduce a dedicated publish-containers workflow triggered after stable releases.
Unify container build and publish logic via scripts, add buildx-based multi-tag publishing,
default base image resolution, and Arch alias tags for latest/version/stable.
https://chatgpt.com/share/693c836b-0b00-800f-9536-9e273abd0fb5