Add resolve_batches, check_unify_batch_dtype, and entry-type From impls

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Contents

Adds batch type resolution for SuperArray and SuperArrayV for the allow_mixed_array_batches feature.

• Array::check_unify_batch_dtype converts an array to a target Field dtype using existing cast methods, falling back to an all-null array for incompatible families.
  - SuperArrayV::resolve_batches and SuperArray::resolve_batches apply per-batch resolution with categorical dictionary merge.
• Added From impls for SuperArrayV
• SuperArrayV::consolidate returns a zero-row typed array on empty views instead of panicking.