Stations past the nearest-12 cutoff silently fell back to straight-line,
which explained the remaining app-vs-Apple-Maps gaps (e.g. 3.5 straight-line
vs 5.9 road). Raise the per-pass cap to 40 and route every station within a
25 km straight-line radius (covers the 15 mi max search window) so any station
the widget/Live Activity/list can show gets a real road distance.
Also harden the new cache tests against persistent keychain state across
invocations (reset in setUp) so they pass deterministically.