fix: check dim1 for ORB descriptor feature count, not dim0

af_orb returns descriptors shaped [8, n_features] (8 uint32 words per
256-bit descriptor, column-major).  dim0 is always 8; dim1 is the
feature count.  The test was checking d0 which always equals 8, not n.

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

Author: dmjio

test/ArrayFire/VisionSpec.hs

@@ -119,11 +119,11 @@ spec = describe "Vision spec" $ do
   --  ORB
   -- ------------------------------------------------------------------ --
   describe "orb" $ do
-    it "descriptor row count equals getFeaturesNum" $ skipOnBrokenBackend $ do
+    it "descriptor column count equals getFeaturesNum" $ skipOnBrokenBackend $ do
       let (feats, descs) = A.orb orbImg 0.1 500 1.5 4 False
           n              = A.getFeaturesNum feats
-          (d0, _, _, _)  = A.getDims (descs :: A.Array Float)
-      d0 `shouldBe` n
+          (_, d1, _, _)  = A.getDims (descs :: A.Array Float)
+      d1 `shouldBe` n
 
     it "all coordinate arrays are consistent with getFeaturesNum" $ skipOnBrokenBackend $ do
       let (feats, _) = A.orb orbImg 0.1 500 1.5 4 False