SFS -> Zarr conversion script

[Aseemrd]

What

Adds sfs_to_egoverse_zarr.py — takes Scale task IDs, downloads SFS data, and writes local .zarr episodes via ZarrWriter.

Writer fix (zarr_writer.py)

_write_language_annotations tried to build a numpy structured dtype with VariableLengthBytes() as a field — numpy can't interpret Zarr-only types, so it crashed with TypeError.

Fix: JSON-encode each annotation row to UTF-8 bytes and store as a flat VariableLengthBytes array — same pattern the image writer already uses.

[aidang3019]

• SFS -> Zarr conversion script #208 👈 (View in Graphite)
• Zarr writing utils #198 : 4 other dependent PRs (#199 , #200 , #212 and 1 other)
• Zarr Reading #197
• main

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