PNG Stalkers v45 no-despawn sound fix

This rebuild fixes the instant disappear bug:
- The visible PNG stalker spawns first and will NOT be killed just because the invisible hitbox has a setup issue.
- Every spawn function calls /function pngstalksafe:init internally.
- No vanilla zombie/giant flash.
- Uses invisible interaction hitboxes for damage.
- Interaction hitboxes have 200 HP.
- Hurt sound plays when the hitbox is attacked.
- Chase sound plays on spawn and loops while the visible PNG is nearby.
- Rudolph and Run Rabbit Run are included and alternate on spawn.
- Songs are NOT automatically stopped half a second later.
- Darkness/blindness applies near stalkers.
- No broken scoreboard random commands.
- jester_grin is not recursive.

Testing:
 /reload
 /function pngstalksafe:test_chase_sound
 /function pngstalksafe:spawn/red_stalker
 /function pngstalksafe:spawn/jester_grin
