Aetherial Realms

## Aetherial Realms 1.1.0

### New
- **Natural Nether arrivals:** when a new Nether portal is made in a Sky Islands world, it's now built on the nearest natural Nether island (up to 128 blocks away) instead of over the void.
- **Linked portals:** a portal moved onto an island stays paired with the Overworld portal that created it. Going back takes you to your original portal instead of making a new one somewhere else, and using the same Overworld portal again reuses the island portal.
- **Biome-themed emergency islands:** if no natural island is close enough, the emergency arrival island now matches its biome: nylium, roots and fungi in crimson and warped forests, soul soil in soul sand valleys, basalt and magma in basalt deltas. It has a flat clearing around the portal, low hills, quartz and gold ore, and glowstone or shroomlight hanging underneath.

### Notes
- Portals built in existing worlds before this update keep their old placement; new portals use the new behavior.
- Fortresses and bastions are the mod's island-anchored versions. Find them with `/locate structure aetherialrealms:nether_fortress` and `aetherialrealms:nether_bastion` (`minecraft:fortress` won't find them).