perf(stark): optimize non-packed constraint evaluation

Packing during constraint evaluation requires the prover to allocate temporary buffers for storing the transposed field elements. Creating these requires a linear pass over the traces before even starting constraint evaluation. In the scalar path, we can just pass a reference to the row, which would reduce allocation and remove a linear pass over the trace (both being particularly useful for WASM).

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Ported from https://github.com/0xMiden/p3-miden/issues/51

Look at the constraint evaluation code in the stark module, likely in `miden-vm/src/stark/`. Identify where packing and temporary buffer allocation occurs. Understand the scalar path and how to pass a reference to a row instead. Review the linked issue from p3-miden for context. Testing involves ensuring the optimization works correctly and does not break existing proofs.

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