ClayGrounds v0.2.0 live-test datapack hotfix

Observed in latest.log:
1. DAI experience creation/world bootstrap succeeded.
2. Minecraft 26.2 rejected scalar minecraft:custom_model_data values.
3. Minecraft 26.2 rejected multi-entity selectors as direct /damage targets.
4. Custom enemies repeatedly walked/fell from thin terrain and died on the flat preset floor at Y=-60.
5. Resource pack particle sprite warnings are resource-pack-side and are not modified by this datapack hotfix.

Datapack changes:
- custom_model_data=N -> custom_model_data={floats:[N.0f]}
- item_display component NBT updated to structured custom_model_data maps.
- AoE combat now executes /damage once per selected enemy with a temporary cg_attack_source player tag.
- Added claygrounds:enemy/safety.
- Added periodic fire resistance to custom carrier mobs.
- Rebuilt Solmere, Sunwash Strand, Verdant Steps, Claycrest Ruins, and Sunken Grotto with connected, tapered terrain.
- Guaranteed solid floor + open headroom at every authored enemy spawn, boss spawn, and player spawn.
- Kept v0.2.0 resource-pack IDs and gameplay coordinates.

Validation performed:
- All JSON parsed.
- All referenced ClayGrounds functions resolve.
- No legacy scalar custom_model_data remains in .mcfunction files.
- No direct multi-target `damage @e[...]` command remains.
- No /fill exceeds 32,768 blocks.
- Every authored spawn anchor has solid support and cleared headroom in the final worldgen command order.
