Holographic Saturation I: Universal Reciprocal Geometry, Entropic Screening, and Galactic Phenomenology

We formulate a relativistic theory of a bounded complex field I=s eiθI=\sqrt{s}\,e^{i\theta}I=seiθ, with 0<s<10<s<10<s<1, derived from a constrained parent action. Matter, electromagnetic fields, tensor modes, and the Einstein-Hilbert sector couple to a single reciprocal physical metric, while the scalar dynamics remain canonical on an auxiliary seed metric. In the static weak-field limit, the same scalar potential controls non-relativistic motion, lensing, and Shapiro delay. The theory has one physical propagation cone, satisfies cT=cγc_T=c_\gammacT=cγ, and gives γPPN=1\gamma_{\rm PPN}=1γPPN=1, with vanishing leading preferred-frame parameters in the near zone. A zero-normalised Kullback-Leibler potential governs local rigidity without contributing an arbitrary vacuum offset. The constrained system propagates two tensor and two scalar degrees of freedom. The canonical charged branch is stable but behaves as a stiff component, whereas a distinct Born-Infeld kinetic-ceiling branch reproduces cold-dark-matter behaviour at linear order. The scalar coupling is too weak to provide the galactic mass directly and instead modulates the clustering condensate. The framework relates the discrete vacuum scale to the empirical galactic acceleration scale without using cosmological or galaxy-fit parameters, while identifying nonlinear condensate dynamics, strong-field matching, and radiative completion as the principal open problems.