chore: track model binaries with git lfs

The Hub rejects binary files pushed through plain git and requires
them to go through LFS, so the artifact cannot reach it otherwise.

The patterns are declared before the artifact is added so that the binary
never enters the object database as a blob; converting afterwards would
leave a copy behind that only a history rewrite could remove.

.gitattributes

@@ -0,0 +1,5 @@
+# The Hub requires binary files to be stored through LFS rather than as plain git
+# blobs. Declared for both model formats in every repository so that the four stay
+# structurally identical, even where the artifact of the moment happens to be JSON.
+*.npz filter=lfs diff=lfs merge=lfs -text
+*.joblib filter=lfs diff=lfs merge=lfs -text