The Two-Loop Anomalous Magnetic Moment from Foam Topology: Structural Identification of C₂

Identifies the foam origin of all four terms in C₂ = 197/144 + π²/12 − π²ln2/2 + 3ζ(3)/4 = −0.328479. The denominators (12, 144) are N_gauge and N_gauge². The threshold ln2 = ln(λ_Eg/2) = ln((C_A+1)/2), exact when C_A=3. The winding coefficient 3/4 = C_A/(C_A+1). The rational −91 = −λ_T2g×(F−1). Every constant is derived from UFFT. Zero free parameters. Status: structural identification; formal derivation from the two-loop D-mode path integral is the next step.