Skyveil Cloudlands Pass 3 notes

Added cloud-island safety/life improvements:
- Skyveil cloud block registrations now mark the blocks as invalid mob spawn surfaces.
- Generated cloud islands maintain at least two Allays by default, using config limits and nearby checks.
- Added /skyveilcloudlands populate_allays_near <radius> for already-generated islands.
- Automatic player-adjacent generation scans a wider loaded-chunk radius by default so the high sky fills in more quickly while exploring.
- The wider generation remains bounded and does not intentionally force-load distant chunks; Minecraft view/server distance still control what can render from far away.
