DB: Backup to object storage and DB offline mode

[Peyton-Spencer]

We had a Turso outage where users could not get their balances, thus could not prompt the LLM whatsoever as we must check the user balance beforehand.

We need failover solutions to keep the app online when this happens.

• [ ] unprocessed receipts queue -> pushed to object storage
• [ ] balances backup array -> pushed to object storage
• [ ] when DB online -> process receipts in queue, then delete from object storage

Consider min instances = 1 in order to leverage keep alive connections, and drastically drop secrets manager usage.