Tailstech Worldgen v2 — Minecraft 1.21.1 / NeoForge

Current changes
===============
- Removes vanilla ruined portals.
- Removes vanilla desert wells.
- Adds rare flower-field decoration to plains/meadows.
- Overrides Ice & Fire CE dragon biome tags:
  * Fire dragons: deserts, badlands, savannas.
  * Ice dragons: cold/snowy/frozen biomes.
  * Lightning dragons: high/windswept mountain biomes.

Ice & Fire CE uses the same structure_gen biome tags for both surface roosts
and underground caves, so these rules affect both.

Worldgen changes affect newly generated chunks only.
