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/autogen.sh

@@ -0,0 +1,44 @@
+#!/bin/sh
+
+# Run this script to generate the configure script and other files that will
+# be included in the distribution.  These files are not checked in because they
+# are automatically generated.
+
+set -e
+
+if [ ! -z "$@" ]; then
+  for argument in "$@"; do
+    case $argument in
+	  # make curl silent
+      "-s")
+        curlopts="-s"
+        ;;
+    esac
+  done
+fi
+
+# Check that we're being run from the right directory.
+if test ! -f src/google/protobuf/stubs/common.h; then
+  cat >&2 << __EOF__
+Could not find source code.  Make sure you are running this script from the
+root of the distribution tree.
+__EOF__
+  exit 1
+fi
+
+set -ex
+
+# The absence of a m4 directory in googletest causes autoreconf to fail when
+# building under the CentOS docker image. It's a warning in regular build on
+# Ubuntu/gLinux as well. (This is only needed if git submodules have been
+# initialized, which is typically only needed for testing; see the installation
+# instructions for details.)
+if test -d third_party/googletest; then
+  mkdir -p third_party/googletest/m4
+fi
+
+# TODO(kenton):  Remove the ",no-obsolete" part and fix the resulting warnings.
+autoreconf -f -i -Wall,no-obsolete
+
+rm -rf autom4te.cache config.h.in~
+exit 0