FuzNugz Special Creeper DP - Minecraft Java 1.20.1

Adds:
- one persistent special creeper only
- distant hill/mountain stalking
- peeking behavior
- window stalking
- mine-finding heuristics using torches, lanterns, rails, and tunnel clues
- exact 2-second look-at disappearance in stalking phases
- final hunt phase with vanilla AI/walking/chasing enabled
- glass-breaking heuristic for windows near the player
- final close-range hit that ends the encounter and permanently prevents the special creeper from being recreated

IMPORTANT LIMITATION:
A pure datapack cannot perfectly tell whether a block was placed by a player. Glass/glass panes and illuminated tunnel clues are therefore used as practical heuristics. For highly intelligent pathfinding, exact player-built structure detection, and a custom renderer/animation system, the Forge Java mod remains the stronger implementation.

GROUNDING / TELEPORT SAFETY UPDATE
-----------------------------------
Stalking, peeking, window, and mine-finding repositioning now use Java Edition
/spreadplayers in `under` mode to resolve the special creeper onto a surface
instead of preserving an arbitrary Y coordinate. This is intended to prevent
mid-air and wall-interior stalking positions.

FUNCTION TEST:
After installing and /reload, run: /function fzcreepypasta:test
If autocomplete does not show fzcreepypasta, the datapack itself is not loaded/enabled.


TWO-WAY 2-SECOND DISAPPEAR BEHAVIOR
During stalking phases 3-4, directly looking at the special creeper starts a 40-tick (2-second) timer. Looking away before 40 ticks cancels that look-at timer. After it has been seen, looking away starts a separate 40-tick timer. Reaching 40 ticks on either timer hides/repositions the same special creeper.

Unkillable: the special creeper has Invulnerable:1b enforced every tick and cannot be damaged/hit. Normal creepers are unaffected.
