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 :)

Found and shipped the five largest code folds (one svg Icon wrapper, one Set helper, single-homed types/helpers, two API twin helpers, dead jaahd code): -432/+284 lines, behaviour unchanged. Recon measured 0.04% duplication and no dead module, so no massive cut exists short of a comment-density policy; AWS credential bundling deferred. Quick gate, 1476 API + 2652 web + 362 jaahd tests green; visual check done, icons render unchanged; blind review PASS. PR #6950 queued in the merge lane. Memory: used mem-25288, mem-25697; proposed 1 qa.