Palette: seven roles (accent, good, caution added; highlight renamed alarm); no hard-coded colours left

background, foreground, subdued, accent (emphasis without danger), and the state
gradient good → caution → alarm; surface and onFill derived. smart-serow's
four-key themes still load (highlight = alarm; the new roles fall back).
Material's scheme follows: buttons in accent instead of the alarm colour.
Link state, mock banner, signal tiles, raw log, checklist button and marks,
camera page all take palette roles.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01DDwfd6Ki8UfG4hK6W5YpJz

lib/widgets/stat_box.dart

@@ -2,7 +2,7 @@
 // every readout is a box that takes its share of a row (`flex`) and sizes its type
 // from its own height, so a layout is a grid of boxes, and a value changing digits
 // never moves anything. Value in foreground with tabular figures, unit and label in
-// subdued; a warning turns the value to highlight.
+// subdued; a warning turns the value to alarm.
 //
 // Added for Yukart: [dim]. A missing or stale value is a normal state in a car
 // (app guideline 2), shown in subdued rather than hidden.
@@ -28,7 +28,7 @@ class StatBox extends StatelessWidget {
   final String label;
   final int flex;
 
-  /// If it returns true, the value shows in highlight.
+  /// If it returns true, the value shows in alarm.
   final bool Function()? isWarning;
 
   /// Missing or stale: the value shows in subdued.
@@ -41,7 +41,7 @@ class StatBox extends StatelessWidget {
     final valueColor = dim
         ? theme.subdued
         : warning
-        ? theme.highlight
+        ? theme.alarm
         : theme.foreground;
 
     return Expanded(
@@ -168,7 +168,7 @@ class StatBoxMain extends StatelessWidget {
                           color: dim
                               ? theme.subdued
                               : warning
-                              ? theme.highlight
+                              ? theme.alarm
                               : theme.foreground,
                           height: 1,
                         ),