Dark Matter as Topological Phase Persistence of the Existence Equation

Evidence Paper V. A single nonlinear wave equation (1/c²)Ψ_tt = ∇²Ψ + λΨ - α|Ψ|²Ψ produces flat galaxy rotation curves (±6-10% plateau flatness), reproduces the Radial Acceleration Relation (MDF up to 11.3x), and dissolves the cusp-core problem. 18-parameter sweep establishes flat curve as structural attractor. Phase energy fraction f_phase = 52.5% ± 1.3% is a topological invariant. No gravity, no dark matter, no MOND.