Imports write strategies to the local library, but folders went through
FolderProvider.createFolder, which fills in the store and parent from the
screen. Signed in, My Library opens on the cloud store, so a dropped folder or
restored backup made its folders in the cloud while its strategies stayed on
this computer, pointing at folder ids the local library doesn't have. And a
library backup restored from inside a folder put its top-level folders in that
folder while its top-level strategies went to the top level.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>