ATEMControl

A big under-the-hood update: the UI hasn't changed, but the entire networking stack has been rewritten. • Networking migrated to Apple's native Network framework — connections come up faster and stay stable. • Fixed multiple crashes when parsing packets from current ATEM firmware. Unknown port types and tally states no longer take the app down. • Hardened tally updates, source selection and keyer interactions against out-of-range errors — buttons can't crash the app anymore. • Clean automatic recovery after a brief loss of connectivity — no need to relaunch. • Codebase cleanup, dropped legacy dependencies — the app is now smaller.