style: update the focus outline in the menu item component (#29753)

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## **Description**

This PR updates the outline style when the user navigates menu items
using the TAB key. This ensures the user can clearly identify which item
is currently focused.

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## **Related issues**

#26728

## **Manual testing steps**

1. Open the menu
2. Navigate through the items using the TAB key
3. Verify that the outline is displayed correctly on the focused item

## **Screenshots/Recordings**

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before and after of your change. -->

### **Before**

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### **After**


https://www.loom.com/share/25a3748a1a8b49e6b3cf617ccf791240?sid=cbe7a8d6-46d9-431a-a0dd-682c6cf209a2

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- [x] I've completed the PR template to the best of my ability
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Not required for external contributors.

## **Pre-merge reviewer checklist**

- [x] I've manually tested the PR (e.g. pull and build branch, run the
app, test code being changed).
- [x] I confirm that this PR addresses all acceptance criteria described
in the ticket it closes and includes the necessary testing evidence such
as recordings and or screenshots.

Author: matteoscurati

ui/components/ui/menu/menu.scss

@@ -42,6 +42,11 @@
     background: var(--color-background-default-hover);
   }
 
+  &:focus {
+    outline: 2px solid var(--color-primary-default);
+    outline-offset: -2px;
+  }
+
   &__icon {
     margin-right: 8px;
     grid-row: 1 / span 2;