Next refactors

lib/presentation/chat/chat_state.dart

@@ -4,6 +4,18 @@ import 'package:trainhub_flutter/domain/entities/chat_message.dart';
 
 part 'chat_state.freezed.dart';
 
+enum ThinkingStepStatus { pending, running, completed, error }
+
+@freezed
+class ThinkingStep with _$ThinkingStep {
+  const factory ThinkingStep({
+    required String id,
+    required String title,
+    @Default(ThinkingStepStatus.running) ThinkingStepStatus status,
+    String? details,
+  }) = _ThinkingStep;
+}
+
 @freezed
 class ChatState with _$ChatState {
   const factory ChatState({
@@ -11,5 +23,7 @@ class ChatState with _$ChatState {
     ChatSessionEntity? activeSession,
     @Default([]) List<ChatMessageEntity> messages,
     @Default(false) bool isTyping,
+    @Default([]) List<ThinkingStep> thinkingSteps,
+    String? streamingContent,
   }) = _ChatState;
 }