refactor(ui): standardize page layouts and component styling

Introduce structural CSS classes for page shells, headers, and surface cards
Update primary theme color to red and neutral to zinc across the application

app.config.ts

@@ -1,8 +1,8 @@
 export default defineAppConfig({
   ui: {
     colors: {
-      primary: 'amber',
-      neutral: 'stone'
+      primary: 'red',
+      neutral: 'zinc'
     }
   }
 })