Write tensors to outDir as sharded safetensors. Returns shard layout,
total byte size, total parameter count, and the (single source of truth)
index object. An index file is written only when there is more than one
shard — matching the loader's expectation that a lone model.safetensors
carries no sidecar index.
Write
tensorstooutDiras sharded safetensors. Returns shard layout, total byte size, total parameter count, and the (single source of truth) index object. An index file is written only when there is more than one shard — matching the loader's expectation that a lonemodel.safetensorscarries no sidecar index.