Identify and implement top 5 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 :)

Implemented the top 5 reductions left after the 11709/12036 sweeps (6 read loaders → useApiRead; account Owner select → shared OwnershipRadios; useOwnOrgId + OwnOrgGate; shared nextSort; one Repository control): −51 net lines/22 files. Census found no product-neutral massive lever; Terraform repeats, v1 refusal guard and two retired-key windows need a decision (report). Quick gate pass, 2906 changed-area tests green, visual check done (radios good at 1280/390), review lane pass. PR #7543 queued to the merge lane.