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 :)

Measured the tree (jscpd incl. ~700K test lines, ts-prune, zero-importer scans): at its floor. Shipped the safe folds in PR #7843 (bedrock pager onto follow_pages, billing clock/act-as helpers single-homed, 2 web suites on shared render; lanes' pager tests added, net -1). Decided to keep the documented API doors and older-jaahd fields; NodeGroupDialog→detail page deferred as a UX rebuild. Quick gate + 403 changed-area tests green; PR queued to the merge lane. No UI surface affected. Memory: used mem-25288, mem-35380, mem-35895; proposed 1 qa (mem-36193).