Reduce codebase by implementing top five 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 :)

Implemented 5 evidence-backed reductions, net −612 lines/76 files: web task-form test clones (−410), Python test helpers into shared homes (−182), API micro-duplicates (−33), list pages onto LoadFailedState/NoMatchesState, Credential/Group/Feature pages onto DetailPage + retired nodelinks_none. Scans show the repo is near its floor (0.01% dup, 0 dead exports/defs), so "massively" was not reachable; migration squash, legacy skynet aliases and a shared detail-read hook are named as deferred follow-ups. Quick gate green, changed-area suites green (web 2528, api 3900+, jaahd 196, infra 313), visual check done on live stack at 1440/390. PR #6928 queued to the merge lane. Memory: used mem-25288; proposed 1 gotcha (mem-25827).