fix pivot_table duplicates on py3.14 with old numpy

found the real issue - searchsorted is broken with python 3.14 + numpy 1.26. it's not compress_group_index, it's the compressor calculation in unstack that uses searchsorted.

just fallback to the unique/return_index approach for this combo, same as what the non-sorted path does.

works with 100k rows now.

Author: AKHIL-149

pandas/core/reshape/reshape.py

@@ -234,7 +234,16 @@ def _make_selectors(self) -> None:
         self.group_index = comp_index
         self.mask = mask
         if self.sort:
-            self.compressor = comp_index.searchsorted(np.arange(ngroups))
+            import sys
+            # GH 63314: avoid searchsorted bug with py3.14 + numpy < 2.0
+            numpy_major = int(np.__version__.split('.')[0])
+            has_searchsorted_bug = sys.version_info >= (3, 14) and numpy_major < 2
+
+            if has_searchsorted_bug:
+                # use manual approach instead of buggy searchsorted
+                self.compressor = np.sort(np.unique(comp_index, return_index=True)[1])
+            else:
+                self.compressor = comp_index.searchsorted(np.arange(ngroups))
         else:
             self.compressor = np.sort(np.unique(comp_index, return_index=True)[1])