feat: Add quick search to EntityGrid with date-based contact sorting

- Add search-as-you-type functionality with 500ms debounce
- Implement search across contact names and DIDs, project names and handleIds
- Add loading spinner and dynamic clear button
- Add $contactsByDateAdded() method to PlatformServiceMixin for newest-first sorting
- Update GiftedDialog to use date-based contact ordering
- Maintain backward compatibility with existing $contacts() alphabetical sorting
- Add proper cleanup for search timeouts on component unmount

The search feature provides real-time filtering with visual feedback,
while the new sorting ensures recently added contacts appear first.

src/components/GiftedDialog.vue

@@ -231,7 +231,7 @@ export default class GiftedDialog extends Vue {
         apiServer: this.apiServer,
       });
 
-      this.allContacts = await this.$contacts();
+      this.allContacts = await this.$contactsByDateAdded();
 
       this.allMyDids = await retrieveAccountDids();