The Continuum — Part II: Proton Structure, the Electron Shell, and the Constants alpha_fs, K_tau

Building on the postulate and logical genesis established in Part I, we develop the internal structure of the toroidal T(2,3) vortex that constitutes the proton. We show that translational stability requires a minimum of three sub-vortices with Z3 symmetry, and derive from this structure spin 1/2 (from the trefoil knot's topology), the nuclear magnetic moment, and electric charge as flow direction. We describe the electron shell as the proton's own permanent flux membrane, and the free electron as a vortex ring detached by photon impact - completing the cycle with the recombination mechanism. From this same topological structure we derive the fine-structure constant as the sum of three geometric phase-space volumes, alpha_fs^-1 = pi + pi^2 + 4*pi^3, and the torsion constant K_tau, whose nature as pure quantum coherence between the knot's two winding modes is characterized by an exact algebraic identity. A correction based on K_tau^2, due to the knot's intrinsic curvature in S3, alpha_fs^-1 = pi + pi^2 + 4*pi^3 - (2*pi^3/3)*K_tau^2, reduces the discrepancy from alpha_fs from 2.22 ppm to 0.37 ppm. The resulting topological proton radius, r_p = 4*hbar/(m_p*c) = 0.8412 fm, agrees with the CODATA value to 0.043%, and its dependence on probe scale naturally explains the proton radius puzzle observed with muonic hydrogen. We finally discuss the ratio m_p/m_e = 6*pi^5: the factor 6 has a triple, independent topological origin, while the exponent of pi remains, honestly, a numerical coincidence not yet derived from first principles. This work constitutes Part II of a series. Subsequent parts develop, on the same foundations, the Koide relation and the CKM/PMNS mixing angles (Part III), and emergent gravity (Part IV). Keywords: trefoil knot, sub-vortices, topological spin, electron shell, fine-structure constant, torsion constant, proton radius.