feat: Add minor widget and asset refinements

lib/features/chat/widgets/assistant_message_widget.dart

@@ -693,7 +693,7 @@ class _AssistantMessageWidgetState extends ConsumerState<AssistantMessageWidget>
           );
 
     _cachedAvatar = Padding(
-      padding: const EdgeInsets.only(bottom: 8),
+      padding: const EdgeInsets.only(bottom: Spacing.md),
       child: Row(
         children: [
           leading,

lib/features/chat/widgets/modern_chat_input.dart

@@ -9,7 +9,6 @@ import 'package:flutter_riverpod/flutter_riverpod.dart';
 
 import 'dart:io' show Platform;
 import 'dart:async';
-import 'dart:typed_data';
 import 'dart:ui';
 import 'dart:math' as math;
 import '../providers/chat_providers.dart';