When a Joomla package has a sub-package that is a git submodule with an
empty or missing source directory (e.g. failed CI checkout), the packager
now falls back to downloading the latest stable release ZIP from the
submodule's Gitea remote.
Also supports pre-staged ZIPs in the output directory, allowing manual
or workflow-based pre-population of sub-package archives.
Claude-Session: https://claude.ai/code/session_01MbEjBtsSjPuTWhqqrMS2wG