refactor(gui): reorganize GUI includes and introduce new components

- Updated include paths for various GUI-related headers to improve organization and clarity.
- Introduced new components for better modularity, including PaletteEditorWidget and EditorCardManager.
- Refactored existing code to utilize the new components, ensuring consistency across the GUI subsystem.

Benefits:
- Enhances maintainability and readability of the GUI code.
- Facilitates future enhancements and optimizations within the GUI subsystem.

src/app/platform/font_loader.cc

@@ -10,7 +10,7 @@
 #include "absl/strings/str_cat.h"
 #include "absl/strings/str_format.h"
 #include "util/file_util.h"
-#include "app/gui/icons.h"
+#include "app/gui/core/icons.h"
 #include "imgui/imgui.h"
 #include "util/macro.h"
 

src/app/platform/font_loader.mm

@@ -3,7 +3,7 @@
 #import <CoreText/CoreText.h>
 #include <TargetConditionals.h>
 
-#include "app/gui/icons.h"
+#include "app/gui/core/icons.h"
 #include "imgui/imgui.h"
 
 #if TARGET_OS_IPHONE == 1 || TARGET_IPHONE_SIMULATOR == 1