shiftArrF_spec (KFC: the Lemma 10 controlled shift (`u = 1`) with the fine-cost rotation)

The following holds (Lean statement, in the scope of module Solutions.KFCShift):

theorem NLogN.KFC.shiftArrF_spec [NeZero Q] (i : Fin n) (c : Fin n → ZMod Q)
    (hc : ∀ j, i ≤ j → c j = 0) (A C : Shape) (hsh : sh = A ++ Q :: C)
    (hA : (Λ.pos i : ℕ) = A.length) (t : IState HS) (xs : List ℤ) (w Bb : ℕ) (R : List Item)
    (hlen : xs.length = AModel.vol sh) (hb : Bnd w xs) (hB1 : 1 ≤ AModel.vol C) (hQ1 : 1 ≤ Q)
    (hP1 : 1 ≤ AModel.vol A) (hV : zsz ((AModel.vol A * (Q * AModel.vol C) : ℕ) : ℤ) ≤ Bb)
    (hQ2 : zsz ((2 * Q : ℕ) : ℤ) ≤ Bb) (h0 : t.G 0 = ints xs ++ R) :
    IRuns I iprog (shF Q (AModel.vol A) (AModel.vol C) (A.zip (KIL.csOf Λ c A))) t
      (t.upd 0 (ints (shiftArr Λ i 1 c 0 xs) ++ R))
      (NLogN.KFC.cRotF (AModel.vol A) Q (AModel.vol C) w + 400000 * (A.length + 1) * AModel.vol A * (Bb + 2) + 13000 * (Bb + 2))

Context. The lemma belongs to the part KFC: the Lemma 10 controlled shift (u = 1) with the fine-cost rotation: rotF_shift_spec: rotF with the offset table offs Λ c A on stack 14 computes shiftArr Λ i 1 c 0 xs (same denotation as KIL.rotP_shift_spec), cost cRotF.

Formalization Note. This lemma belongs to the item-language (IL) layer of the integer-multiplication-kappa campaign: tape-level programs (register programs over 64 item stacks of the NLogN multitape framework, definition bundles IntMul_HvdH_M_Defs1–IntMul_HvdH_M_Defs8) that implement the data-movement primitives of the OpenAI preprint Integer multiplication below $n\log n$ (field moves, row split/merge, shifts, the uniform Proposition 11 interchange, Lemma 12 with fine $O(1)$-per-element costs, Gaussian record primitives, Proposition 14 pieces) with exact list denotations from the array-model bundles IntMul_Kappa_K_Defs* and explicit cost bounds. All names refer to the definition bundles up to IntMul_Kappa_K_Defs18.