feat: Lemmas related to evaluating indices of tensors

[jstoobysmith]

Added lemmas related to the evaluation of indices of tensors.

Claude used for part of the proofs.

[github-actions]

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[zhikaip]

is it possible to add more documentation to explain what evalT permT etc. are doing? I understand this is part of a larger refactor and maybe you want to do it at the end, so I've approved this for now

[jstoobysmith]

@zhikaip Made enough changes that this probably need another review before merging.

[jstoobysmith]

Going to merge this now.