Reduce repository code volume by implementing top

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 :)

Re-measured: no massive reduction exists (458 clone lines in 852K after 3 prior sweeps). Implemented the 5 real folds (mirrors workflow jobs, mirror/auth test fixtures, relay-scan helper, tenancy interpolable()): net −62 lines, quick gate + 165 API/14 tool tests green, review lanes pass. PR #7493 queued in the merge lane. ADR-level candidates (legacy launch runtime, generated types.ts, test volume, Windows, lock pins) named in the report, not taken. No UI surface affected. Memory: used mem-31667, mem-31297; proposed 1 qa.