We currently have Queue, PHP-Queue, and DonationQueue abstractions for our PHP code. Push towards consolidating, probably towards an isolated module like PHP-Queue. DonationQueue is sort of legit because it wraps PHP-Queue, maybe rename so that the class's responsibilities are more clear, it's just a message normalization helper. Maybe push that functionality into a new thing.
Drop KeyValue store.
The generalized queue functionality is the responsibility of PHP-Queue. Any configuration or financial extensions should be implemented in SmashPig.