feat(core+backend/X11): 实现窗口边框管理和焦点跟随鼠标

tests/core/CMakeLists.txt

@@ -4,6 +4,7 @@ add_executable(${TEST_APP_NAME}
     ${CMAKE_CURRENT_SOURCE_DIR}/main.c
     ${SOURCE_DIR}/base/color.c
     ${SOURCE_DIR}/base/log.c
+    ${SOURCE_DIR}/base/window_list.c
     ${SOURCE_DIR}/backend/output_utils.c
     ${SOURCE_DIR}/config/defaults.c
     ${SOURCE_DIR}/config/loader.c