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

Merged #4580: one after-commit helper replaces 5 hooks, a shared Pager replaces 6 footers, and a duplicate of zonedTime is gone. Net -120 prod lines; full gate green. Not massive: no larger safe duplication found. Deferred: moving the billing outbox to DBOS (needs a design call).