PUBLISH variable should be wired in projio's scaffold/init codegen so new packag

PUBLISH variable should be wired in projio's scaffold/init codegen so new packages get PUBLISH ?= <path> in their Makefile automatically.

Currently each package's Makefile needs manual setup — biblio, indexio, and notio had it; pipeio and codio were missed and fell back to bare twine upload which prompts for a token interactively.

Proposal: add a publish_script key to .projio/config.yml (or user-level ~/.config/projio/config.yml) under runtime:, similar to projio_python and datalad_bin. The Makefile codegen in projio init / projio.mk should emit PUBLISH ?= <configured path>. Default: publish_pypi.sh from infra/bin if it exists on the system.