Use iOS16 CoreML model for keypoint preview

Replace the CoreML fp32 model with the previously-committed iOS16-all
variant, keeping the current file name.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

preview/coreml/rfdetr_keypoint_preview_coreml_fp32.pte

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
-oid sha256:250396199d4a8c8225d871e703c187db1dccac285fd2bab6e32b10a788356747
-size 147593973
+oid sha256:0455df2be527a464bba13876ab5cd1a2becbfb0e7a2d0dcc826c5e095bd6bffe
+size 147743446