Top 5 code reduction opportunities implementation

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 :)

No PR: the tree is at its dedup floor. Re-measured with 5 detectors incl. tests (82 removable Python lines, 1 web window, 0 dead defs, 0 orphans); 4 same-body PRs already merged today. 5 remaining levers (5–10k lines each) are owner decisions, named with gates in the report; retiring-columns contraction verified ready. Memory: used mem-32217; proposed 1 qa.