chore: Refactor CMakeLists.txt and app.cmake files for better organization

src/app/core/core.cmake

@@ -0,0 +1,32 @@
+set(
+  YAZE_APP_CORE_SRC
+  app/core/common.cc
+  app/core/controller.cc
+  app/core/labeling.cc
+  app/emu/emulator.cc
+  app/core/message.cc
+)
+
+if (WIN32 OR MINGW OR UNIX AND NOT APPLE)
+  list(APPEND YAZE_APP_CORE_SRC
+    app/core/platform/font_loader.cc
+    app/core/platform/clipboard.cc
+    app/core/platform/file_dialog.cc
+  )
+endif()
+
+if(APPLE)
+    list(APPEND YAZE_APP_CORE_SRC 
+      app/core/platform/file_dialog.mm
+      app/core/platform/app_delegate.mm
+      app/core/platform/font_loader.mm
+      app/core/platform/clipboard.mm
+      app/core/platform/file_path.mm
+    )
+
+    find_library(COCOA_LIBRARY Cocoa)
+    if(NOT COCOA_LIBRARY)
+        message(FATAL_ERROR "Cocoa not found")
+    endif()
+    set(CMAKE_EXE_LINKER_FLAGS "-framework ServiceManagement -framework Foundation -framework Cocoa")
+endif()