One shared window (journey/card-gaps.ts, CARD_GAP) describes the open road
after each chapter's panel in section-local progress; the district relight
and cutover, the last yard lift and the relay station's beams now key off
it instead of their own numbers, and the chapter margin widens from 44vh
to 48vh so the gap reads as a stretch of road. Unit tests prove every
payoff's peak sits inside the window for every chapter span.
A 240-degree SVG dial with a spring needle, three-digit readout, unit
label, warning lamp (BRAKE / OVERDRIVE / ENGINE OFF), trip odometer and
gear chip, driven by the journey's own frame loop from the scroll drive,
route progress, navigator state, scene ignition and the high beam. Hover
or focus shows route, exit and time on the road; a click toggles km/h
and mph (remembered). The model and DOM driver load as a lazy chunk so
the initial bundle grows by about 1.3 kB gzipped; reduced motion snaps
the readout, and the bay hides below 1280px.
