Repaint the scene art in the new palette

Workout scenes are warm orange hills under a peach sky, meditation slate
hills with a soft orange sun, must-do sand to charcoal. Goal and group
scenes keep deriving from their colour, with a warmer sky and sun.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01KhQh614DMeYoQEH9SoMRUw

frontend/lib/Grounded/utils/CommonUtils.dart

@@ -375,12 +375,12 @@ List<Color> goalScene(Color accent) {
 
   return <Color>[
     shade(0.80, 0.55),
-    const Color(0xFFF6EFE2),
-    const Color(0xFFFFD9A0),
+    const Color(0xFFF5F1EE),
+    const Color(0xFFF7B08C),
     shade(0.66, 0.6),
     shade(0.48, 0.8),
     shade(0.30, 0.9),
-    const Color(0xFFE5793D),
+    colorAccent,
   ];
 }