Identify and implement top code reduction opportunities

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 :)

Identified the top 5 code-reduction opportunities; shipped 4 as PR #6999 (−67 net: AWS region validation single-homed, web shared sx/UUID helpers, bucket-target fold, headline builder fold; quick gate green, 801 web + ~700 api tests green, visual check done, all surfaces clean). #5, the NodeLink v1 wire (~800–1000 LOC), is deferred until every node is on the v2 package. Scans show the tree is already at the floor for duplication. PR queued to the merge lane (state: queued). Memory: used mem-25697; proposed 0.