Identify and implement top code reduction opportunities

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 :)

Net -140 lines, PR #7782 queued to the merge lane: test setup single-homed across api/jaahd/web (-113, no test removed), one ProductionQaList for Deployments/Incidents (-24), mypy baseline -3. Three of five cuts measured under the 20-line bar and reverted (json11 paging -2, runner-hook atomic write ~-16, jaahd older-CP tolerance -1). Fresh dead-code and clone scans show the tree is at its floor; remaining large cuts need an owner call (legacy launch, Windows, generated edition maps, GitHub Connect). Quick gate pass; 313 API, 217 jaahd, 2582 web tests green; code-reviewer and verifier lanes PASS. Visual check done: both pages clean at 1440 and 390. Memory: used mem-25288, mem-35351; proposed 1 qa.