Massively Reduce Repo Code with DBOS

Identify an opportunity to massively reduce the amount of code (lines of code) in any part of the repo: - Similar functionality that can be unified and reused - Code that has been valuable but no more - Front end component or group of them duplicates another component functionality. Use the most modern and nice looking - Move to DBOS and get rid of supporting functionality relying on DBOS - etc. Implement it

Token-billing outbox moved onto DBOS (transactional enqueue, delayed-successor retries); hand-rolled drain/claim/backoff engine deleted. Full gate green, PR #4852 merged, Jaah Deploy OK. App LOC +68 until the named follow-up drops overlap shims+table; no large dead code found.