Stack/07 world mesh

[JucanAndreiDaniel]

Summary

Rebuilds the world-mesh build pipeline onto MeshDataArray + Burst write jobs, makes chunk slicing texture-aware, and bumps the cache format.

Changes

• New job/data — WorldMeshWriteJob and WorldMeshChunkData for jobified mesh writes.
• Builder — WorldMeshBuilder/AbstractMeshBuilder rebuilt: a single GetPolygon sweep caches each chunk's expanded vertex count, writes go through Burst jobs into AllocateWritableMeshData, and the error path does JobHandle.Complete() + Dispose() before rethrowing (no native leak).
• Slicing — WorldChunkCacheCreatorDomain/PreCachingScene slice chunks using the cached TextureArray info; StaticCacheVersion bumped.
• Shaders — lit shaders updated for the rebuilt mesh layout.

How to test

• Delete the static cache and pre-cache a world; confirm load completes and chunk count/visuals are correct.
• Verify world rendering looks the same.
• spawn at night to see if lights work properly