PNG Stalkers Safe Blackout + Music for Forge 1.20.1

No Java classes. Uses vanilla text_display entities, functions, fonts, and sounds.

Commands:
/function pngstalksafe:auto/on
/function pngstalksafe:auto/off
/function pngstalksafe:kill_all
/function pngstalksafe:spawn/all
/function pngstalksafe:spawn/puppet_marionette
/function pngstalksafe:spawn/jester_grin

Behavior:
- Auto-spawn is ON by default.
- Stalkers follow players but do not attack.
- Within 5 blocks: scary noise, 2 second blackout, then they vanish.
- Puppet Marionette and Jester Grin play the included music cue when a player is looking at them / has them in view.
