Identify and implement top 5 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 :)

Measured the tree first (jscpd ≤0.08% dup, knip/vulture 0 dead): no massive cut exists without stripping rationale comments. Shipped the real levers (production-QA detail read+status+mono shared; OwnValueBlock tests merged; 17 zero-reference names dropped), net −57 lines; one lever superseded by develop; identity revision-2 contraction named as follow-up. Visual check done (both detail pages, 1280/448px, clean). PR #7899 queued to the merge lane after a develop merge; quick gate, lint, tsc, vitest, host+API suites green.