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 every reduction lever (copy-paste, clones, dead defs/exports, orphans, retired surfaces, test audit): none massive; repo already single-homed. Shipped the 5 largest real unifications (sql_page rosters, keyset.page, from_row, utc_iso_z, redact_userinfo): ~-70 app lines, 7 helpers gone. PR #7904 merged by the lane as 543dafed; its Jaah Deploy was superseded (left alone). Criterion flagged as too strong. No UI surface affected.