style: fix line length in ContactsView ternary operator

- Break long CSS class strings into multiple concatenated lines
- Ensure all lines are under 100 characters for better readability
- Maintain same functionality and styling behavior
- Improve code maintainability and readability

Fixes: Long lines in conditional CSS class assignment

src/components/GiftedPrompts.vue

@@ -227,7 +227,7 @@ export default class GivenPrompts extends Vue {
 
     let someContactDbIndex = Math.floor(Math.random() * this.numContacts);
     let count = 0;
-    
+
     // as long as the index has an entry, loop
     while (
       this.shownContactDbIndices[someContactDbIndex] != null &&