Top 5 code reduction opportunities implementation

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 :)

Measured the repo (jscpd, knip, vulture, 8 recon probes): no massive duplication exists. Shipped the 5 real single-home fixes: retired 2 preference keys, apiFetch for 4 raw fetches, one home for agent-count copy, Stop hooks on run_guard, 2 in-file Python clones. Quick gate green, changed-area tests green (1 pre-existing API failure proven outside the diff). PR #7457 queued in the merge lane. Deferred: useQuery→useApiRead sweep (behavioural). Visual check done: Plans list renders clean; "3+ agents" wording unified. Memory: used mem-31313; proposed 1 gotcha.