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 :)

Shipped the five largest unifications the tree allows (ui/Toast, SearchBox debounce home, ui/feed/ListStates, app/one_line, _org partials): 32 files +119/−233, quick gate + full vitest + API suites green, review lane passed. PR #7023 queued to the merge lane. Recon found no massive lever without a product decision; six are named as deferred. Visual check done at 1280/390px: all surfaces clean. Memory: used mem-25288; proposed none.