@bn

implemented a sparse voxel object format:

1. header (32 bytes): * 0x4D454B45 (magic "MEKE")
   * world dimensions ($w, h, d$)
   * directory dimensions ($dw, dh, dd$)
   * brick pool count
2. directory (page table):
   * a 3d array of uint32 indices.
   * maps chunks to specific bricks in the pool.
   * index 0 is reserved for wātea (empty air).
3. brick pool: * a contiguous blob of $8 \times 8 \times 8$ (512 byte) voxels.
   * deduplicated via binary fingerprinting