feature: localization (#32)

* build: add nlohmann/json library

* build(deps): add harfbuzz dependency

* feat(cmake): add guard to reject macOS builds

* feat(font): add HarfBuzz shaping and replace font with unifont

* feat(localization): add i18n support with en_US and zh_CN translations

Implement Localization class to load JSON translation files. Replace hardcoded strings in UI with translation keys and update sliders/combo buttons to use dynamic text.

* feat(localization): detect system locale for language default

* feat(settings): add language selection option with restart notification

* fix: use vckpg to add freetype on windows

CMakeLists.txt

@@ -1,4 +1,9 @@
 cmake_minimum_required(VERSION 3.21)
+
+if(APPLE)
+    message(FATAL_ERROR "This game does not support macOS")
+endif()
+
 project(Cubed LANGUAGES C CXX)
 
 set(CMAKE_CXX_STANDARD 23)
@@ -141,6 +146,7 @@ target_link_libraries(${PROJECT_NAME}
         absl::flat_hash_map
         zstd::zstd
         OpenAL::OpenAL
+        harfbuzz::harfbuzz
         $<$<PLATFORM_ID:Windows>:ws2_32>
 
 )