no19_Gravitational Entanglement Entropy Density from Deficit Divergence_V2

This version adds a new section (section 5: Black Hole as a Double Domain Wall System) that provides a structural interpretation of the Schwarzschild black hole in the QBN framework. The black hole is described as a double domain wall system consisting of two distinct topological phase boundaries: an outer domain wall at the event horizon (separating the non-saturated exterior from the saturated interior) and an inner domain wall at the Planck core boundary (separating the saturated mantle from the SU(2)_6 topological core). The outer wall is a holographic screen whose entropy obeys the Bekenstein-Hawking area law, while the inner wall carries a topological invariant entropy independent of the black hole mass. The flow of EPR pairs from the Planck core through the saturated mantle to the horizon provides a microscopic realisation of the holographic principle. All other sections of the paper remain unchanged.