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

Net −503 lines: one shared chat model-round loop (site_chat → support_agent.converse), duplicated API/web test setup collapsed. Reviews PASS; gate stages green on rerun (2 load-flaky e2e pass isolated). PR #5330 merged, Jaah Deploy success.