Durable, per server store for upload recovery records. Each record captures
everything needed to finish the exact ResourceMap write for one metadata
document, keyed by that metadata PID, so a crash between "metadata
committed" and "ResourceMap committed" can be replayed on the next load.
Backed by
PersistentStorage (localforage/IndexedDB), so records
survive a tab crash. Each record stores the exact serialized ResourceMap
bytes the interrupted upload had prepared. Limited server side
reconstruction is a separate, explicit recovery choice when no record can
be retrieved.