Solar-System Gravitational Refraction and Shapiro Delay in a Continuous-Medium Vacuum

General Relativity (GR) models the bending of light and the Shapiro time delay as geometric consequences of spacetime curvature. In this paper, we derive these classical Solar-System optical signatures from an alternative continuous-medium kinematics framework. Within this framework, light is modeled as a high-frequency wave packet propagating through a continuous vacuum medium, rather than a discrete particle in a vacuum. The local mass density modifies the substrate's relaxation properties, yielding an effective optical refractive index. Utilizing Fermat's principle and classical wave optics, we demonstrate that this effective medium refraction strictly yields a solar limb deflection angle of exactly 1.75 arcseconds and a Shapiro time delay perfectly consistent with Cassini spacecraft tracking data. The framework mathematically recovers all existing weak-field predictions of GR through effective optical refraction, and obviates the need for supplementary scalar fields found in models like chameleon gravity. Furthermore, we propose a sub-leading frequencydependent dispersion signature, anchored to the Grand Unified Theory (GUT) scale, which distinguishes this medium model from vacuum GR and is testable via future high-energy gamma-ray astrometry.