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 :)

Implemented the five largest code reductions left after 12 sweeps (net −117 lines, 23 files): 7 route pairs onto on_session, 6 web same-shape folds, lease_drain/trigger_config/mfa helpers. Tree is at its floor; bigger levers are product-gated (named in report). Quick gate, 568 API + 302 web tests green; 3 blind lanes pass. PR #7857 queued to the merge lane. Visual check done: Tasks and user pages render cleanly. Memory: used mem-25288/35380/35895/32667/32031; proposed 1 qa.