Reduce codebase by implementing top five refactoring

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 :)

Scans found the tree nearly clone-free (0.02% web, 0.09% python, 0 structural at 20 lines), so no massive cut exists without removing product. Implemented the five mechanisms still held in >2 copies (web slug, API template slug, three API test fixtures): 18 files, -46 net. PR #7386 merged by the lane (ef68c961); Jaah Deploy succeeded. Visual check: no UI surface affected. Memory: used mem-22588; proposed none.