Information-Causality Field and the Unified Field Theory Based on 11-Dimensional T^3 Torus Fractal Geometry -- Paper VI: Quantum Gravity and Flavor Physics: 7D Topological Winding Numbers, Lepton Mass Hierarchy, Neutrino Oscillations, and Gravitation

We present a complete field-theoretical formulation unifying quantum gravity and flavor physics on an internal 7-dimensional X^7 manifold with G_2 holonomy embedded in the T^3 x Z_900 topological framework. The three-generation structure of Standard Model fermions is proved topologically via the Betti numbers of X^7, yielding N_gen = 1/2|b_3 - b_2| = 3. By parameterizing internal topological winding numbers n ∈ {1,2,3}, we derive the tree-level tau lepton mass m_τ = 1761.45 MeV and set a strict upper bound on the absolute neutrino mass m_ν ≤ 0.048 eV with bimaximal flavor mixing. Furthermore, the gravitational sector resolves black hole curvature singularities through a 225l_P topological soliton core repulsive barrier, modifying the metric near r → 0. We predict that binary black hole mergers generate secondary gravitational wave echoes with a time delay Δt_echo = 25.55 ms and a characteristic 39.1 Hz frequency comb spectrum, providing a testable signature for Advanced LIGO, Virgo, and KAGRA.