strategies:listInventory returns where every folder and listed strategy
of the caller's own library sits, read in one transaction. Export
Library lists the cloud folder by folder; while another device moves
strategies between folders, two such listings can miss the same
strategy, so the export could not prove its backup held everything.
Checked against this inventory, it can. Read-only and additive: no
existing client calls it.

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