Module cache/decompressed-chunk-cache

L0 Decompressed Chunk Cache - Caches decoded zarr chunks to avoid repeated Blosc decompression.

This cache sits above the L1/L2 compressed caches and stores the OUTPUT of zarrita's codec.decode() - fully decompressed TypedArrays ready for use.

Performance impact:

• L1 hit without L0: ~1μs lookup + ~2ms decompression = ~2ms
• L0 hit: ~1μs lookup + 0ms decompression = ~1μs (2000x faster)

For 4 attributes (positions, colors, radii, sharpness):

• Without L0: ~8ms decompression overhead per view update
• With L0: ~0.004ms (essentially zero)