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 :)

Audited the tree (0.05% duplication, no dead modules) and shipped the five largest behaviour-neutral reductions: net −283 lines over 60 files (web transcript fold, shared OAuth connect helpers, api test seams, guard selftests, write-sites registry). Quick gate and 15k tests green; blind security/code/verifier lanes pass. PR #7066 queued to the merge lane. Decided: ticket transcript keeps the newer bubble look (task asked for the modern component). Deferred: old-package nodelink wire, legacy redirects.