Spacetime Substantivalism XIIII: Covariant Constitutive Effective Field Theory of Spacetime Propagation — A Unified Multi-Probe Constraint from Cosmology and Gravitational Waves (实质时空论第十四篇:协变本构时空传播有效场论——基于宇宙学与引力波的多探针统一约束研究)

This is the 14th paper in the "Spacetime Substantivalism (Constitutive Spacetime Dynamics, CSSD)" series. This work further demonstrates the fundamental properties of spacetime as revealed by gravitational waves: its substantivity, extreme rigidity, and internal homogeneity. It provides a unified explanation for the mildness of the Cosmic Microwave Background (CMB), the electromagnetic nature of spacetime and photonic materials, and the constancy of light-speed as determined by the lattice structure. Within this framework, the emergence of the Lorentz transformation factor is shown to be medium-dependent, and the Hubble tension is resolved as a necessary consequence of constitutive propagation. This model offers a unified integration of Dark Matter, Dark Energy, Black Holes, the Matter-Antimatter asymmetry, Inflation, and a cosmic expansion governed by the constancy of light-speed. On the empirical level, we construct a Covariant Effective Field Theory (EFT) that preserves Einstein's field equations while introducing a constitutive propagation kernel. A joint Bayesian analysis using Planck CMB, Pantheon+ Supernovae, BAO, and GWTC-3 data yields a significant preference over the Lambda-CDM model. We predict a definitive splitting between electromagnetic and gravitational-wave luminosity distances, providing a falsifiable signature for next-generation multi-messenger observatories like LISA and the Einstein Telescope.