GeoModels 2.3.0: CheckCor validation for model 85 and model 89.

The shared CheckCor() switch now reads existing parameter positions and checks
finite values, positive scales, normalized sep in [-1,1], and smoothness.
Model 85 also checks the coupled generalized Wendland shape inequalities
using the spatial dimension already managed by the existing internals.

The native GeoFixedMarginSTValid() remains as a defensive check for direct
kernel evaluations and finite-difference optimizer trials. It is not called
by CheckCor() anymore. Public R function signatures and parameter names
are unchanged. Correlation formulas and native evaluation are untouched.

R / R CMD check not available in this build environment.
