feat: Implement AgentChatWidget for conversational AI interaction and add ASCII logo support

src/app/gui/widgets/agent_chat_widget.h

@@ -0,0 +1,83 @@
+#ifndef YAZE_APP_GUI_WIDGETS_AGENT_CHAT_WIDGET_H_
+#define YAZE_APP_GUI_WIDGETS_AGENT_CHAT_WIDGET_H_
+
+#include <memory>
+#include <string>
+#include <vector>
+
+#include "absl/status/status.h"
+#include "cli/service/agent/conversational_agent_service.h"
+#include "app/rom.h"
+
+namespace yaze {
+namespace app {
+namespace gui {
+
+/**
+ * @class AgentChatWidget
+ * @brief ImGui widget for conversational AI agent interaction
+ * 
+ * Provides a chat-like interface in the YAZE GUI for interacting with the
+ * z3ed AI agent. Shares the same backend as the TUI chat interface.
+ */
+class AgentChatWidget {
+ public:
+  AgentChatWidget();
+  ~AgentChatWidget();
+
+  // Initialize with ROM context
+  void Initialize(Rom* rom);
+
+  // Main render function - call this in your ImGui loop
+  void Render(bool* p_open = nullptr);
+
+  // Load/save chat history
+  absl::Status LoadHistory(const std::string& filepath);
+  absl::Status SaveHistory(const std::string& filepath);
+  
+  // Clear conversation history
+  void ClearHistory();
+
+  // Get the underlying service for advanced usage
+  cli::agent::ConversationalAgentService* GetService() {
+    return agent_service_.get();
+  }
+
+ private:
+  void RenderChatHistory();
+  void RenderInputArea();
+  void RenderToolbar();
+  void RenderMessageBubble(const cli::agent::ChatMessage& msg, int index);
+  void RenderTableFromJson(const std::string& json_str);
+  
+  void SendMessage(const std::string& message);
+  void ScrollToBottom();
+
+  // UI State
+  char input_buffer_[4096];
+  bool scroll_to_bottom_;
+  bool auto_scroll_;
+  bool show_timestamps_;
+  bool show_reasoning_;
+  float message_spacing_;
+  
+  // Agent service
+  std::unique_ptr<cli::agent::ConversationalAgentService> agent_service_;
+  Rom* rom_;
+  
+  // UI colors
+  struct Colors {
+    ImVec4 user_bubble;
+    ImVec4 agent_bubble;
+    ImVec4 system_text;
+    ImVec4 error_text;
+    ImVec4 tool_call_bg;
+    ImVec4 timestamp_text;
+  } colors_;
+};
+
+}  // namespace gui
+}  // namespace app
+}  // namespace yaze
+
+#endif  // YAZE_APP_GUI_WIDGETS_AGENT_CHAT_WIDGET_H_