feat(circuit/frontier): the contraction recursion as one native machine, reduced to the resource analysis (Theorem D.1, T2.9) - #1970

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: actions/checkout@v4. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/

Not declared at the PR head: `p_t`, `p_j`. Advisory only; see the job summary.

`Cslib.GaloisRingArith.liftO` and `Cslib.Circuits.Frontier.NativeChild.RingO` (Complexity/Computability/Circuit/Frontier/TensorNetwork/NativeChild.lean:396) share a 161-node subterm, 98% of the smaller body, built from `Valuation.integer`, `AdjoinRoot`, `Rat`, `Rat.commRing`, `Polynomial.map`, `Int.castRingHom`. Advisory only; see the job summary.

`Cslib.GaloisRingArith.rootO` and `Cslib.Circuits.Frontier.NativeChild.RingO` (Complexity/Computability/Circuit/Frontier/TensorNetwork/NativeChild.lean:396) share a 161-node subterm, 98% of the smaller body, built from `Valuation.integer`, `AdjoinRoot`, `Rat`, `Rat.commRing`, `Polynomial.map`, `Int.castRingHom`. Advisory only; see the job summary.

`Cslib.Circuits.Frontier.FastContraction.WF` and `Cslib.leastIrreducible` (Complexity/Foundations/FieldTheory/Finite/BinaryField.lean:154) share a 213-node subterm, 59% of the smaller body, built from `Irreducible`, `Polynomial`, `ZMod`, `Nat.fact_prime_two`, `Polynomial.semiring`. Advisory only; see the job summary.