Rename app/ directory to game/

game/CMakeLists.txt

@@ -0,0 +1,12 @@
+add_executable(game main.c)
+set_default_target_options(game)
+target_include_directories(game PUBLIC include)
+
+target_link_libraries(game PRIVATE
+  engine
+  m
+  LibXml2::LibXml2
+  SDL2::SDL2
+  SDL2::SDL2main
+  SDL2_image::SDL2_image
+)