FigpackRef.load()/show() broken on DataJoint 2.3 (remote get_folder AttributeError; file branch caches None)

[dimitri-yatsenko]

FigpackRef.load() (and therefore show()) is non-functional against DataJoint 2.3, on both storage paths. Surfaced during review of #2, which intentionally left load() untouched to keep scope tight.

Defects

1. Remote branch calls a method that no longer exists. ref.py load() calls self._backend.get_folder(self.path, str(local_path)), but DataJoint 2.3's StorageBackend has no get_folder (verified against datajoint/storage.py on 2.3.x — the folder download idiom is now backend.fs.get(full_path, dst, recursive=True), as used by serve_under). Any non-file store raises AttributeError.

2. File branch caches a non-view. The file branch caches figpack.view_figure(local_path). Per figpack ≥ 0.3, view_figure() serves the figure over HTTP and returns None rather than reconstructing a FigpackView, so load() returns/caches None and show() does not display a reconstructed view.

Because both load() and show() are featured in the class docstring and the package README/__init__ example (ref.show()), the advertised primary API currently fails.

Proposed fix

• Rewrite the remote branch to use backend.fs.get(backend._full_path(self.path), dst, recursive=True) (mirroring serve_under), and validate against a real remote store (see the fs.get recursive-semantics caveat noted in Render-ready codec: fix save() call, store data-only Zarr, add FigpackRef.serve_under #2).
• Reconstruct a view from the downloaded data.zarr using a figpack ≥ 0.3 API that returns a view object (not the HTTP-serving view_figure), or redefine load()/show() in terms of the serve_under bundle.
• Interim (ship with Render-ready codec: fix save() call, store data-only Zarr, add FigpackRef.serve_under #2): make load() raise a clear NotImplementedError/DataJointError pointing at serve_under, so the deferred state is explicit rather than an AttributeError or a silently cached None.

Refs #2.