true when the last sync couldn't reach the server (or the vault was opened from the offline cache)
The server ETag at the last sync (compare with a vault event's etag), or undefined before one.
Downloads, merges local edits and uploads them (conditional PUT, merge and retry on 412). With
localChanged: false it first asks the server with a HEAD and stops there when nothing changed.
Sets a field and syncs it up.
An opened account vault: a kdbxweb database kept in sync with
vaults/<id>.