Identify and Implement Repo Code Reduction

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

Cut 787 net lines (PR #4876, merged, Jaah Deploy green). Deleted the one-shot Windows probe and the v1 credential arm; moved hand-rolled dialogs, rows, pickers and switches onto ui primitives. Full gate green. Larger DBOS/overlap cuts deferred (see report).