feat: Enhance Agent Chat History Popup with Retro Animations

- Introduced retro-style animations including pulsing borders, scanline effects, and glitch animations to the Agent Chat History Popup, enhancing visual appeal.
- Updated message display with terminal-inspired styling, including color-coded sender labels and retro separators.
- Improved header design with a pulsing glow effect and animated status indicators for unread messages, enriching user interaction.
- Refactored drawing methods to accommodate new visual effects while maintaining existing functionality.

src/app/editor/agent/agent_editor.h

@@ -103,6 +103,12 @@ class AgentEditor : public Editor {
     int max_tool_iterations = 4;
   };
   
+  // Retro hacker animation state
+  float pulse_animation_ = 0.0f;
+  float scanline_offset_ = 0.0f;
+  float glitch_timer_ = 0.0f;
+  int blink_counter_ = 0;
+  
   AgentConfig GetCurrentConfig() const;
   void ApplyConfig(const AgentConfig& config);