Add 3 world test files, all tests pass

[MichaelFisher1997]

Summary: Added 3 test files with 50+ unit tests for the world module targeting dev:

Tests Added:

• block_biome_tests.zig (47 tests): Biome.getSurfaceBlock(), Biome.getFillerBlock(), Biome.getOceanFloorBlock() for all biome types including transition biomes

• chunk_mesh_tests.zig (5 tests): ChunkMesh.init creates null allocations, deinitWithoutRHI cleanup, subchunk arrays initialization

• chunk_storage_extended_tests.zig (12 tests): ChunkStorage.getOrCreate idempotency, IChunkStorage interface wrapper, totalVertexCount, isChunkRenderable, next_job_token incrementing

All tests pass (zig build test exits with code 0).

Triggered by scheduled workflow

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