Updates grass and tree spawning to use the parent's RNG,
ensuring consistent random generation based on the seed.
This removes redundant RNG instances and ensures that grass and
trees are generated predictably for a given cell.
Adds procedural ground tile generation with chunking for improved performance.
Includes:
- Ground tile entity with debug text and cell information
- Grass and tree placement based on cell data
- Ground shader for visual representation
- Chunk loading and unloading system based on player position
