chore: update SCSS preprocessor API to modern-compiler (#8659)

Configured SCSS preprocessor options to use the `modern-compiler` API,
aligning with the new Sass API standards and preparing for Dart Sass
2.0.0. This change prevents deprecation warnings and ensures future
compatibility by transitioning away from the legacy JS API.


https://sass-lang.com/documentation/breaking-changes/legacy-js-api/

Got rid of 
![Screenshot from 2024-11-05
15-25-09](https://github.com/user-attachments/assets/c13827de-6ab4-40ab-af4c-d1a4f8cb7b3e)

frontend/vite.config.mts

@@ -23,6 +23,13 @@ const vitestConfig = vitestDefineConfig({
         environment: 'jsdom',
         exclude: [...configDefaults.exclude, '**/cypress/**'],
     },
+    css: {
+        preprocessorOptions: {
+            scss: {
+                api: 'modern-compiler'
+            }
+        }
+    }
 });
 
 export default mergeConfig(