[ENH] Update GeoModel to include and reset geophysics input

Expose `geophysics_input` and integrate gravity gradient calculation during deserialization. This ensures proper resetting of geophysics-specific fields when grid data is available.

Author: Leguark

gempy/core/data/geo_model.py

@@ -15,6 +15,7 @@
 from gempy_engine.core.data.interpolation_input import InterpolationInput
 from gempy_engine.core.data.raw_arrays_solution import RawArraysSolution
 from gempy_engine.core.data.transforms import Transform, GlobalAnisotropy
+from gempy_engine.modules.geophysics.gravity_gradient import calculate_gravity_gradient
 from .encoders.converters import instantiate_if_necessary
 from .encoders.json_geomodel_encoder import encode_numpy_array
 from .grid import Grid
@@ -62,7 +63,7 @@ class GeoModel(BaseModel):
     # region GemPy engine data types
     _interpolation_options: InterpolationOptions  #: The interpolation options provided by the user.
 
-    geophysics_input: GeophysicsInput = Field(default=None, exclude=True)  #: The geophysics input of the geological model.
+    geophysics_input: GeophysicsInput = Field(default=None, exclude=False)  #: The geophysics input of the geological model.
     input_transform: Transform = Field(default=None, exclude=False)  #: The transformation used in the geological model for input points.
 
     interpolation_grid: EngineGrid = Field(default=None, exclude=True)  #: ptional grid used for interpolation. Can be seen as a cache field.
@@ -303,16 +304,22 @@ def add_surface_points(self, X: Sequence[float], Y: Sequence[float], Z: Sequence
     @classmethod
     def deserialize_properties(cls, data: Union["GeoModel", dict], constructor: ModelWrapValidatorHandler["GeoModel"]) -> "GeoModel":
         match data:
-            case GeoModel():
+            case GeoModel(): 
                 return data
-            case dict():
+            case dict(): # 
                 instance: GeoModel = constructor(data)
                 instantiate_if_necessary(
                     data=data,
                     key="_interpolation_options",
                     type=InterpolationOptions
                 )
                 instance._interpolation_options = data.get("_interpolation_options")
+                
+                # * Reset geophysics if necessary
+                centered_grid = instance.grid.centered_grid
+                if centered_grid is not None and instance.geophysics_input is not None:
+                    instance.geophysics_input.tz = calculate_gravity_gradient(centered_grid)
+                
                 return instance
             case _:
                 raise ValidationError

test/test_modules/_geophysics_TO_UPDATE/test_gravity.test_gravity.verify/2-layers.approved.txt

@@ -103,6 +103,14 @@
         "_octree_levels": -1,
         "active_grids": 1058
     },
+    "geophysics_input": {
+        "tz": [],
+        "densities": [
+            2.6,
+            2.4,
+            3.2
+        ]
+    },
     "input_transform": {
         "position": [
             -6.0,