refactor: Update quick actions description and enhance AppCustomizationPage layout

- Revised the quick actions description in multiple languages to clarify their purpose as "Quickpills in chat."
- Adjusted the layout of AppCustomizationPage by reintroducing the quick pills section for improved user interaction.
- Modified spacing between UI elements for better visual consistency and usability.
- Streamlined the component structure to enhance maintainability and readability.

lib/l10n/app_localizations_en.dart

@@ -875,8 +875,7 @@ class AppLocalizationsEn extends AppLocalizations {
       'Theme, language, voice, and quickpills';
 
   @override
-  String get quickActionsDescription =>
-      'Pick up to two shortcuts to pin near the composer';
+  String get quickActionsDescription => 'Quickpills in chat';
 
   @override
   String get chatSettings => 'Chat';