Visuality Megabound v500.2 patch

Active Overworld (world0) paths were patched, not just root shader fallbacks.
- Night cloud lighting increased with a dedicated moon-fill baseline.
- Night godrays use a non-zero moon baseline so shadow-map darkness cannot make them disappear.
- 3-layer volumetric clouds build up progressively with rainStrength.
- Rain fog stays white but more transparent.
- Visible rain impact/water-spot overlay added in active composite.fsh.
