Scalar-Tensor Knot-Web Cosmology: From Degeneracy Surface to Topological Selection

Version 3. Major upgrade: the Majorana mass open problem is promoted from Open to Conjecture with proved kinematic skeleton. Summary table: 8 established links (7 proved, 1 conjecture) and 2 open problems. Builds on: No-Go Theorem (DOI: 10.5281/zenodo.18866200) and CS Boundary Completion (DOI: 10.5281/zenodo.18894178). Changelog: v2: Volumetric Traversal Theorem (R ~ t^{2/3} from CS action scaling), Friedmann recovery (ρ ~ R^{-3} from mass conservation), dimension-dependent prediction R(t) ~ t^{(d-1)/3} uniquely selecting d=3. v3: Spin-wall defect mechanism for Majorana mass. Longitudinal spin defect O_(0,1) on boundary torus T² opens odd theta-channel (Lemma 7.2: ϑ₂ → ϑ₁) with leading |sin(Φ/2)| factor…