* Add a dedicated variant of `mat_vec_mul_sparse` for `NonNativeFieldVar`

* Switch to a customized in-circuit nonnative implementation for efficiency

* Comments and tests for `NonNativeUintVar`

* Make `CycleFoldCircuit` a bit smaller

* Faster trusted setup and proof generation by avoiding some nested LCs

* Check the remaining limbs in a more safe way

* Format

* Disable the non-native checks in tests again

* Clarify the group operation in `enforce_equal_unaligned`

* Explain the rationale behind non-native mat-vec multiplication

* Explain the difference with some other impls of `enforce_equal_unaligned`

* Format