Information Protection as a Fundamental Principle VIII: First-Principles Derivation of Spacetime Dimensionality, the Arrow of Time, Maximal Entropy, the Hot Big Bang, and Dark Matter from Internal Network Topology

We derive the dimensionality of spacetime, the holographic entropy bound, the arrow of time, the hot Big Bang, and the nature of dark matter from the information-protection axioms. Spacetime is uniquely (1,3)-dimensional as a consequence of information-cost minimization and spectral dimension matching, without reference to the gauge group. The entropy bound and the final information-saturation attractor are derived with zero free parameters. The thermodynamic arrow of time emerges from the directed graph structure. The hot Big Bang arises from causal diffusion on the product graph, providing homogeneous initial conditions for inflation. Dark matter consists overwhelmingly of topological glueballs from the SU(3) network, with mass approx 7.04 GeV, internal degeneracy 3, and relic abundance matching the Planck measurement. The complete derivation chain from the single parameter ln(chi) to the relic abundance is closed.