Paper II Geometric Origin of Electric Charge, Unified Charge Formula, and First-Principles Derivation of the Fine-Structure Constant

This paper is the second in the Planck Cube Space Theory series. It derives the geometric definition of electric charge, the unified charge formula Q = K·V·ω, and the fine-structure constant α from first principles. Electric charge is shown to be a measure of the radial twist of Planck cubes induced by the spin of an energy bundle (particle). The equality of electron and proton charges follows from the saturation condition Vₑωₑ = Vₚωₚ = (Vω)ₘₐₓ. Fractional quark charges arise from the symmetric threefold division of radial twist capacity within hadrons. The geometric weight sum S = 4π³ + π² + π is derived via continuum regularization, yielding α_ideal = 1/S ≈ 1/137.0363, in agreement with the experimental value to 7 significant figures. Higher-order corrections are identified and quantified.