Identify and implement top five code reduction

Identify top 5 opportunities 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 - A front end component or a group of them duplicate another component/page functionality. Use the most modern and nice looking - etc. Now implement them :)

Five code reductions shipped, net -121 lines (PR #7933, queued to the merge lane): one httpx test harness for the AWS suites, useLinkCodeFlow on usePoll, a typed outcomes scope, one ErrorNote in CredentialEditPage, shared PlanCaps/CustomConnectorBody types. Quick gate green; review and verifier lanes pass. Assumed "massively" was aspirational: every repo-wide sweep found no reduction of that order (details in the report). Deferred: none. Visual check done on the credential editor at desktop and phone, clean. Memory: used mem-25288; none proposed.