Feature: Linux/macOS server-identity gate via libsign.a

fix remote-cursor flicker on Windows controller

macos/CMakeLists.txt

@@ -19,6 +19,7 @@ set(SOURCES
     main.mm
     ../client/Buffer.cpp
     ../client/IOCPClient.cpp
+    ../client/sign_shim_unix.cpp
     ScreenHandler.mm
     InputHandler.mm
     SystemManager.mm
@@ -62,6 +63,11 @@ target_link_libraries(ghost PRIVATE
     ${ACCELERATE_FRAMEWORK}
     ${ICONV_LIBRARY}
     "${CMAKE_SOURCE_DIR}/lib/libzstd.a"
+    # 私有签名库（提供 signMessage / verifyMessage，源码不开源）
+    # 该库由 SimplePlugins 仓库本地构建后放置于 lib/，构建机需先准备好
+    # libsign.a 内部使用 macOS CommonCrypto（HMAC-SHA256），CCHmac 在 libSystem
+    # 中已被 Cocoa/CoreFoundation 等链接自动引入，故此处无需额外 framework
+    "${CMAKE_SOURCE_DIR}/lib/libsign.a"
 )
 
 # Compiler flags