Grid/GridView API unification: mcrfpy.Grid now returns GridView, closes #252

mcrfpy.Grid() now creates a GridView that internally owns a GridData (UIGrid).
The old UIGrid type is renamed to _GridData (internal). Attribute access on Grid
delegates to the underlying UIGrid via tp_getattro/tp_setattro, so all existing
Grid properties (grid_w, grid_h, entities, cells, layers, etc.) work transparently.

Key changes:
- GridView init has two modes: factory (Grid(grid_size=...)) and explicit view
  (Grid(grid=existing_grid, ...)) for future multi-view support
- Entity.grid getter returns GridView wrapper via owning_view back-reference
- Entity.grid setter accepts GridView objects
- GridLayer set_grid handles GridView (extracts underlying UIGrid)
- UIDrawable::removeFromParent handles UIGRIDVIEW type correctly
- UIFrame children init accepts GridView objects
- Animation system supports GridView (center, zoom, shader.* properties)
- PythonObjectCache registration preserves subclass identity
- All 263 tests pass (100%)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/McRFPy_API.cpp

@@ -482,9 +482,9 @@ PyObject* PyInit_mcrfpy()
         &PyDrawableType,
 
         /*UI widgets*/
-        &PyUICaptionType, &PyUISpriteType, &PyUIFrameType, &PyUIEntityType, &PyUIGridType,
+        &PyUICaptionType, &PyUISpriteType, &PyUIFrameType, &PyUIEntityType,
         &PyUILineType, &PyUICircleType, &PyUIArcType, &PyViewport3DType,
-        &mcrfpydef::PyUIGridViewType,
+        &mcrfpydef::PyUIGridViewType,  // #252: GridView IS the primary "Grid" type
 
         /*3D entities*/
         &mcrfpydef::PyEntity3DType, &mcrfpydef::PyEntityCollection3DType,
@@ -547,6 +547,9 @@ PyObject* PyInit_mcrfpy()
     // Types that are used internally but NOT exported to module namespace (#189)
     // These still need PyType_Ready() but are not added to module
     PyTypeObject* internal_types[] = {
+        /*#252: internal grid data type - UIGrid is now internal, GridView is "Grid"*/
+        &PyUIGridType,
+
         /*game map & perspective data - returned by Grid.at() but not directly instantiable*/
         &PyUIGridPointType, &PyUIGridPointStateType,
 
@@ -682,6 +685,11 @@ PyObject* PyInit_mcrfpy()
         t = internal_types[i];
     }
 
+    // #252: Add "GridView" as an alias for the Grid type (which is PyUIGridViewType)
+    // This allows both mcrfpy.Grid(...) and mcrfpy.GridView(...) to work
+    Py_INCREF(&mcrfpydef::PyUIGridViewType);
+    PyModule_AddObject(m, "GridView", (PyObject*)&mcrfpydef::PyUIGridViewType);
+
     // Add default_font and default_texture to module
     McRFPy_API::default_font = std::make_shared<PyFont>("assets/JetbrainsMono.ttf");
     McRFPy_API::default_texture = std::make_shared<PyTexture>("assets/kenney_tinydungeon.png", 16, 16);