Synchronize old recommendation buckets when signing into existing account
As pointed out in #38 (closed) if you sign into an existing account on a new device (or same device after clearing the app data) the app will continue showing recommendations from when the user was anonymous, but will not load their old recommendations list.
New recommendations are of course added to the top of the list properly, but I wonder if we shouldn't also synchronize some of the user's previous recommendation buckets as well.