Dash page and smart-serow's palette, boxed widgets, attitude and G-meter

Ported from smart-serow's HUD: the four-colour palette with dark/bright variants
(same theme JSON format, loaded at runtime; YUKART_THEME picks one), StatBox and
StatBoxMain, WhiskeyMark and AccelGraph. The whole app takes its colours from the
palette. Dash: attitude, G-meter, RPM, GNSS speed, pedal, coolant and telltales,
each from its contracts signal; missing and stale draw in subdued.

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

lib/main.dart

@@ -8,8 +8,10 @@ import 'package:flutter/material.dart';
 import 'boundary.dart';
 import 'camview.dart';
 import 'checklist.dart';
+import 'dash.dart';
 import 'linktest.dart';
 import 'net.dart';
+import 'theme/palette.dart';
 
 /// Override for development, e.g. `--dart-define=YUKART_GW=ws://halogen.local:7700/`.
 const defaultUrl = String.fromEnvironment(
@@ -19,6 +21,7 @@ const defaultUrl = String.fromEnvironment(
 
 Future<void> main() async {
   WidgetsFlutterBinding.ensureInitialized();
+  themes = await Themes.load();
   final usb = UsbLink();
   await usb.bindFor(Uri.parse(defaultUrl));
   final boundary = Boundary(defaultUrl)..start();
@@ -58,6 +61,9 @@ Future<void> main() async {
 
 final navigatorKey = GlobalKey<NavigatorState>();
 
+/// The palette (lib/theme/palette.dart), loaded before the first frame.
+late final Themes themes;
+
 Widget linkTestPage(Boundary b, LinkTest t, UsbLink usb) => LinkTestPage(
   test: t,
   host: Uri.parse(b.url).host,
@@ -77,19 +83,21 @@ class YukartApp extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return MaterialApp(
-      title: 'Yukart',
-      navigatorKey: navigatorKey,
-      debugShowCheckedModeBanner: false,
-      theme: ThemeData(
-        colorSchemeSeed: Colors.teal,
-        brightness: Brightness.dark,
-        useMaterial3: true,
-      ),
-      home: ListenableBuilder(
-        listenable: Listenable.merge([boundary, usb]),
-        builder: (context, _) =>
-            Readout(boundary: boundary, usb: usb, linkTest: linkTest),
+    // Every page takes its colours from the palette; switching dark/bright rebuilds them all.
+    return ListenableBuilder(
+      listenable: themes,
+      builder: (context, _) => MaterialApp(
+        title: 'Yukart',
+        navigatorKey: navigatorKey,
+        debugShowCheckedModeBanner: false,
+        theme: themes.material(),
+        builder: (context, child) =>
+            AppTheme(palette: themes.current, child: child!),
+        home: ListenableBuilder(
+          listenable: Listenable.merge([boundary, usb]),
+          builder: (context, _) =>
+              Readout(boundary: boundary, usb: usb, linkTest: linkTest),
+        ),
       ),
     );
   }
@@ -233,6 +241,15 @@ class LinkBar extends StatelessWidget {
                 Text(
                   'USB link ${usb.up ? 'up' : 'absent'}${usb.bound ? ', bound' : ''}',
                 ),
+              TextButton.icon(
+                onPressed: () => Navigator.of(context).push(
+                  MaterialPageRoute<void>(
+                    builder: (_) => DashPage(boundary: b, themes: themes),
+                  ),
+                ),
+                icon: const Icon(Icons.dashboard),
+                label: const Text('Dash'),
+              ),
               TextButton.icon(
                 onPressed: () => Navigator.of(context).push(
                   MaterialPageRoute<void>(