build: update CI pipeline
refactor: base image
refactor: rewrite to s6-overlay new service format
build: check-new-tags only on main branch
fix: file permissions
build: fix job name
docs: update README
build: fix code format
ci: fix job stage
ci: add shellcheck manual trigger
ci: fix pipeline
ci: fix pipeline variable
ci: fix shellcheck find files
chore: fix shellcheck source
ci: fix to allow shellcheck to load external sources
fix: shellcheck