V3-16: visual identity (token-level pass)

Direction written before code, per the ticket's own step 1: safety orange stays primary (authentic to the domain, not decorative), a new instrument-blue tertiary is reserved for reference readings (max/average) vs the live figure, ground warmed fractionally, no new font, no motion -- both argued for directly rather than left undecided.

Instrument blue reuses RideMap's existing slow-speed gradient color rather than inventing a new one, so 'same colour, same meaning' holds between the map and stat rows. contrastRatio() implements WCAG 2.x directly and is asserted (11 tests, both themes, AA normal/large) rather than eyeballed. Applied to StatRow's new 'reference' flag on record screen and trip detail's Max/Avg speed rows -- a token-level + targeted pass, not an exhaustive re-skin, named as a deliberate scope reduction alongside the two criteria (outdoor sunlight verification, golden tests) this environment genuinely cannot satisfy.

lib/src/ui/detail/trip_detail_screen.dart

@@ -354,10 +354,12 @@ class _Body extends StatelessWidget {
                 StatRow(
                   label: 'Max speed',
                   value: formatSpeed(s.maxSpeedKmh, unit: units),
+                  reference: true,
                 ),
                 StatRow(
                   label: 'Avg moving speed',
                   value: formatSpeed(s.avgMovingSpeedKmh, unit: units),
+                  reference: true,
                 ),
                 StatRow(
                   label: 'Elevation gain',