Reduce codebase by implementing five major 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 :)

Unified the five largest real duplicates the tree offers (project request models, slot_state launch blanks, richtext linkify wrapper, answer_delivery preamble, shared port probe + socket fake): 63 net lines fewer, no behaviour change, quick gate + changed-area suites green. PR #7382 queued to the merge lane. Assumed "massively" is ambition not a threshold: four whole-tree scans show the repo is already single-homed; larger cuts need design decisions (named in report). Memory: none applied.