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/components/stats.dart

@@ -71,11 +71,17 @@ class BigStat extends StatelessWidget {
 }
 
 class StatRow extends StatelessWidget {
-  const StatRow({super.key, required this.label, required this.value});
+  const StatRow({super.key, required this.label, required this.value, this.reference = false});
 
   final String label;
   final String value;
 
+  /// V3-16: true for a figure you compare the live reading against (a max, an average)
+  /// rather than the live reading itself. Colours the value with the instrument-blue
+  /// tertiary instead of the default ink, so the same colour means the same kind of
+  /// number everywhere it appears. See the ticket's Direction section.
+  final bool reference;
+
   @override
   Widget build(BuildContext context) {
     final colors = Theme.of(context).colorScheme;
@@ -89,7 +95,7 @@ class StatRow extends StatelessWidget {
             value,
             style: monoDigits.copyWith(
               fontWeight: FontWeight.w500,
-              color: colors.onSurface,
+              color: reference ? colors.tertiary : colors.onSurface,
             ),
           ),
         ],