fix: add _mappings_sizes_weights_split to InterpolatorRectangular

The property exists on InterpolatorKNN and InterpolatorDelaunay, but
was missing from InterpolatorRectangular, so any rectangular mesh +
split regularization (ConstantSplit, AdaptSplit, AdaptSplitZeroth)
combination raised AttributeError.

Rectangular pixelizations use bilinear interpolation which already
factors in the 4-corner neighbourhood, so split regularization reuses
the same mapping arrays.

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

Author: 2 people

autoarray/inversion/mesh/interpolator/rectangular.py

@@ -305,3 +305,10 @@ def _mappings_sizes_weights(self):
         sizes = 4 * self._xp.ones(len(mappings), dtype="int")
 
         return mappings, sizes, weights
+
+    @cached_property
+    def _mappings_sizes_weights_split(self):
+        # Rectangular pixelizations use bilinear interpolation which already factors
+        # in the 4-corner neighbourhood, so no separate split-cross calculation is
+        # needed — split regularization reuses the same mappings.
+        return self._mappings_sizes_weights