TQNT-V5.15 — Derivation of the R² coefficient from SU(2)_135 first principles

TQNT-V5.15 identifies the R² coefficient of the V5.14 Starobinsky-like inflation potential from the SU(2)_135 Chern-Simons sector. The coefficient is fixed to a = (k+2)5/6 = 1/(6·αEM5), with k = 135 the unique Chern-Simons level of TQNT. Status and honest scope: Reproduces the V5.14 calibration to +11.1%. Predicts As = 1.89 × 10−9 with NO free parameter (Planck observed value: 2.10 × 10−9, -9.9%). ns = 0.967 and r = 3.3 × 10−3 are unchanged with respect to V5.14. The exponent 5 in (k+2)5 is identified by numerical consistency; the full Coleman-Weinberg derivation is deferred to V5.16. Complements the V5 monograph (10.5281/zenodo.19131538) and turns V5.14 into a parameter-free TQNT prediction at the ~10% level for As.