refactor: update app.vue and various components to enhance UI consistency, replace color classes for improved accessibility, and refine layout for better user experience

components/ReserveMeter.vue

@@ -72,7 +72,7 @@ const progressColor = computed(() => {
     case "red":
       return "red";
     default:
-      return "gray";
+      return "neutral";
   }
 });
 
@@ -85,7 +85,7 @@ const badgeColor = computed(() => {
     case "red":
       return "red";
     default:
-      return "gray";
+      return "neutral";
   }
 });