feat(gui): Extract and modularize GUI system from main.cpp

- Create modular GUI architecture with base Panel class
- Implement GUIManager to handle window lifecycle and panel management
- Add Window wrapper class for SDL3/OpenGL context management
- Create specialized panels:
  - ConsolePanel: Colored log output with timestamps
  - CPUPanel: CPU debugging with tabs for registers, memory, and disassembly
  - PerformancePanel: Real-time FPS and frame time monitoring
- Apply modern dark theme with purple accents
- Add comprehensive menu bar (File, Emulation, View, Tools, Help)
- Update CMakeLists.txt to include new gui/ directory structure
- Refactor main.cpp to use the new GUI system
- Cutom theme on switch colors

gui/Panel.h

@@ -0,0 +1,27 @@
+// Copyright 2025 Pound Emulator Project. All rights reserved.
+#pragma once
+
+#include <string>
+#include <imgui.h>
+
+namespace Pound::GUI
+{
+
+    class Panel
+    {
+    public:
+        Panel(const std::string &name) : name(name) {}
+        virtual ~Panel() = default;
+
+        virtual void Render() = 0;
+
+        const std::string &GetName() const { return name; }
+        bool IsVisible() const { return visible; }
+        void SetVisible(bool vis) { visible = vis; }
+
+    protected:
+        std::string name;
+        bool visible = true;
+    };
+
+} // namespace Pound::GUI