Fix outdated references in README and update CHANGELOG

README: fix function names (Once.perform/3, start_option/0),
remove references to nonexistent Majic.Helpers.perform_once/2,
clarify Plug fix_extension is opt-in, fix recycle_threshold typo.

CHANGELOG: remove nonexistent Majic.compile/2, add Fixed section
with all bug fixes, add macOS/Homebrew build support and Woodpecker CI.