residue-calculus: Laurent coefficients, residues, and the circle-integral bridge (RS)

Purely planar (no manifolds, no Jacobian/Forms import). API summary (see docs/design/residue-calculus.md):

• Taylor/Laurent layer: RS.taylorCoeffAt g z₀ j (dslope-iterate Taylor extractor) and RS.laurentCoeffAt f z₀ k (Laurent coefficient via the order presentation), with congruence (_congr), ℂ-linearity (_add/_const_mul/_fun_sum), monomials/shift (_zpow_monomial/_zpow_mul), and the analytic/order compatibility bridges (laurentCoeffAt_of_analyticAt, laurentCoeffAt_order vs meromorphicTrailingCoeffAt).
• Principal parts: RS.principalPartAt f z₀, the decomposition MeromorphicAt.exists_principalPart_add_analyticAt (f =ᶠ[𝓝[≠]] principalPart + analytic), and its uniqueness (eq_principalPart_of_eventuallyEq).
• Residues: RS.resAt f z₀ := laurentCoeffAt f z₀ (-1), its algebra, the derivative lemmas MeromorphicAt.resAt_deriv (= 0) and MeromorphicAt.resAt_deriv_div (= order; the argument- principle atom), and the Serre-pairing atoms resAt_tail_mul/resAt_analyticAt_mul/resAt_mul (Miranda VI.3 shape Σ c_n a_{−1−n}).
• Chart invariance: RS.resAt_comp_mul_deriv — resAt ((f∘φ)·φ') w₀ = resAt f z₀ for a local analytic isomorphism φ (φ w₀ = z₀, deriv φ w₀ ≠ 0); makes Res_p(ω) on a surface chart-independent. Residue of a raw function is NOT chart-invariant — always pair with φ'.
• Integral bridge: RS.circleIntegral_eq_two_pi_I_mul_resAt (∮_{C(z₀,R)} f = 2πi·resAt f z₀, fixed radius) and its small-radius (∀ᶠ R in 𝓝[>] 0) form.
• Germ/ML packaging: RS.meromorphicGermsAt z₀ (ℂ-submodule of meromorphic germs at 𝓝[≠] z₀), RS.laurentCoeffL/RS.resL as →ₗ[ℂ] functionals on it; RS.PrincipalPartData U (Mittag-Leffler data, Forster §17.1–17.2) with Realizes, ofMeromorphicOn, and the algebraic closure lemmas (Realizes.add/.smul/.sub_orderAt_nonneg, realizes_zero_iff).

Routing: this unit is the LOCAL, planar input. ∑ Res = 0 (Stokes) lives in residue-theorem / planar-stokes-atoms; the residue functional H¹(Ω) → ℂ of Serre duality lives in serre-duality-cech/tails. Neither is built here.