feat: 完成 M2 mosh（LAN + tsnet 端到端验证）

- mosh(blinksh/ios C++)+protobuf-lite 交叉编译为 MoshCore.xcframework
  （CommonCrypto 后端、含 arm64 模拟器 slice；绕 autotools 用 CMake 直编 + 手写 config.h）
- tsnet 桥新增 UDP relay（StartMoshRelay：loopback↔tsnet.Dial 逐包搬运）
- MoshSession（pipe↔FILE*/pthread/SIGWINCH）+ MoshConnectScanner（TXCore，+4 单测=39）
- SSHTerminalModel 编排：SSH 引导 mosh-server→解析 MOSH CONNECT→relay→mosh 接管
- LAN 直连 + mosh-over-tsnet 均端到端验证通过，R1(tsnet UDP 数据报语义) 证伪

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

vendor/protobuf/third_party/googletest/CMakeLists.txt

@@ -0,0 +1,31 @@
+cmake_minimum_required(VERSION 2.8.8)
+
+if (CMAKE_VERSION VERSION_LESS "3.1")
+  add_definitions(-std=c++11)
+else()
+  set(CMAKE_CXX_STANDARD 11)
+  set(CMAKE_CXX_STANDARD_REQUIRED ON)
+  set(CMAKE_CXX_EXTENSIONS OFF)
+endif()
+
+if (POLICY CMP0048)
+  cmake_policy(SET CMP0048 NEW)
+endif (POLICY CMP0048)
+
+project(googletest-distribution)
+set(GOOGLETEST_VERSION 1.9.0)
+
+enable_testing()
+
+include(CMakeDependentOption)
+include(GNUInstallDirs)
+
+#Note that googlemock target already builds googletest
+option(BUILD_GMOCK "Builds the googlemock subproject" ON)
+option(INSTALL_GTEST "Enable installation of googletest. (Projects embedding googletest may want to turn this OFF.)" ON)
+
+if(BUILD_GMOCK)
+  add_subdirectory( googlemock )
+else()
+  add_subdirectory( googletest )
+endif()