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 :)

No PR: tree at its dedup floor. Re-measured develop 16c788edc with jscpd (8/60: 218 clone lines, 109 generated), vulture+grep (0 dead), ts-prune (0 dead), test-value detectors (no cut), route/import walk (0 orphans); six same-body PRs already merged today. Five remaining levers are owner-gated (report). Memory: used mem-32217; proposed none.