The nematic-to-smectic A (N-SmA) phase transition has remained one of the principalunsolved problems in statistical physics of condensed matter for over four decades. Experimental measurements of the heat capacity exponent α vary continuously from approximately 0 (3D-XY universality) to approximately 0.5 (tricritical mean-field), depending on the McMillan ratio r = TNA/TNI. No theoretical framework has explained this crossover from first principles. We present a resolution in two parts. Part I (model-independent) shows that the N-SmA transition maps exactly onto the Aubry—André—Harper (AAH) metal—insulator transition at the self-dual critical point V = 2J. This mapping uses only the de Gennes free energy (1972), lattice discretization, and the generic incommensurability of smectic layer spacing and molecular length. At criticality, the energy spectrum is a Cantor set with Hausdorff dimension Ds = 1/2 (Süt˝o 1989), giving ν = 2/3 and predicting that α varies continuously from 0 to 2/3. This qualitative result holds for any irrational frequency α and requires no new physics. Part II (quantitative) identifies the AAH frequency as α = 1/ϕ (golden ratio), producing the five-band Cantor partition. This yields a zero-free-parameter formula:α(r) = 23u2000r−rc1−rcu20004, r > rc; α = 0 otherwisewhere rc = 1−1/ϕ4 = 0.8541 and ϕ = (1+√5)/2. The formula fits 11 experimental compoundsspanning 40 years of published calorimetry with RMS = 0.033, reduced χ2 = 0.47, and all points within 2σ. Zero free parameters.