Massively Reduce Repo Code via Refactoring

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

Repo scan found no massive dup (0.2% clones, no dead files). Shipped DBOS leftovers: deleted pre-DBOS verify_share path, dropped writer-less token_billing_outbox. Quick gate + 1601 tests green; PR #5098 merged, Jaah Deploy green.