Haste Shader V1.1.4 V54 — End environment refinement (branched from V53)

Baseline policy:
- Starts directly from V53. The Gargantua renderer, event-horizon mask, world direction, size, animation, and glow functions are unchanged.
- No terrain, water, Distant Horizons, or End lighting code was altered.

End environment improvements:
- Added two fine, faint world-direction-pinned star populations to add distance without large sparkles.
- Replaced the former simple End nebula strip with a layered indigo/violet/magenta/teal nebula, broad cloud masses, irregular filaments, displaced secondary wisps and naturally dark gaps.
- The nebula texture drifts extremely slowly; star positions and black-hole direction remain world-pinned.
- Added END_NEBULA_STRENGTH to the End settings menu, default 1.0 with options from 0.0 to 2.0.

Validation: ZIP structure and source delimiters checked. Not compiled or tested inside Minecraft.
