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/build/build-mosh.sh

@@ -0,0 +1,76 @@
+#!/bin/bash
+# 交叉编译 mosh(blinksh/ios 分支) + protobuf-lite → MoshCore.xcframework（iOS device/simulator/macOS）。
+# crypto 后端 = Apple CommonCrypto（系统内建）；特性宏由 build/mosh/config.h 手写提供（绕过 autotools）。
+# 产出 library-only xcframework（头文件与 modulemap 由包内 C target 提供，避免 modulemap 撞车，同 CSSHCore 教训）。
+set -euo pipefail
+
+BUILD="$(cd "$(dirname "$0")" && pwd)"          # vendor/build
+VENDOR="$(cd "$BUILD/.." && pwd)"               # vendor
+MOSH_SRC="$VENDOR/mosh/src"
+PROTOBUF="$VENDOR/protobuf"
+PROTOBUF_SRC="$PROTOBUF/src"
+MOSH_CMAKE="$BUILD/mosh"
+OUT="$BUILD/mosh-out"
+ARTIFACTS="$VENDOR/../artifacts"
+IOS_DEPLOY=17.0
+MAC_DEPLOY=14.0
+
+build_slice() {
+  local name="$1" sysname="$2" sysroot="$3" archs="$4" deploy="$5"
+  echo "==================== slice: $name ($archs @ $sysroot) ===================="
+  rm -rf "$OUT/$name"; mkdir -p "$OUT/$name"
+
+  local common=(
+    -G Ninja
+    -DCMAKE_BUILD_TYPE=Release
+    -DCMAKE_SYSTEM_NAME="$sysname"
+    -DCMAKE_OSX_SYSROOT="$sysroot"
+    -DCMAKE_OSX_ARCHITECTURES="$archs"
+    -DCMAKE_OSX_DEPLOYMENT_TARGET="$deploy"
+  )
+
+  # --- protobuf-lite（仅 lite runtime；mosh 的 .proto 是 proto2 + LITE_RUNTIME） ---
+  cmake -S "$PROTOBUF" -B "$OUT/$name/protobuf" "${common[@]}" \
+    -Dprotobuf_BUILD_TESTS=OFF \
+    -Dprotobuf_BUILD_PROTOC_BINARIES=OFF \
+    -Dprotobuf_BUILD_LIBPROTOC=OFF \
+    -Dprotobuf_BUILD_SHARED_LIBS=OFF \
+    -DCMAKE_CXX_STANDARD=14
+  cmake --build "$OUT/$name/protobuf" --target libprotobuf-lite -j8
+
+  # --- moshios（我们的 CMakeLists，编 src/*.cc） ---
+  cmake -S "$MOSH_CMAKE" -B "$OUT/$name/mosh" "${common[@]}" \
+    -DMOSH_SRC="$MOSH_SRC" \
+    -DPROTOBUF_SRC="$PROTOBUF_SRC"
+  cmake --build "$OUT/$name/mosh" -j8
+
+  # --- 合并静态库 → 单一 libMoshCore.a ---
+  libtool -static -o "$OUT/$name/libMoshCore.a" \
+    "$OUT/$name/mosh/libmoshios.a" \
+    "$OUT/$name/protobuf/libprotobuf-lite.a"
+  echo "[+] $name → $(lipo -archs "$OUT/$name/libMoshCore.a")"
+}
+
+pack_xcframework() {
+  echo "==================== packing MoshCore.xcframework (library-only) ===================="
+  rm -rf "$ARTIFACTS/MoshCore.xcframework"; mkdir -p "$ARTIFACTS"
+  local args=()
+  for s in "$@"; do
+    args+=(-library "$OUT/$s/libMoshCore.a")
+  done
+  xcodebuild -create-xcframework "${args[@]}" -output "$ARTIFACTS/MoshCore.xcframework"
+  echo "[+] MoshCore.xcframework:"; ls "$ARTIFACTS/MoshCore.xcframework"
+}
+
+case "${1:-all}" in
+  iossim) build_slice iossim    iOS    iphonesimulator "arm64;x86_64" "$IOS_DEPLOY" ;;
+  device) build_slice ios-arm64 iOS    iphoneos        "arm64"        "$IOS_DEPLOY" ;;
+  macos)  build_slice macos     Darwin macosx          "arm64"        "$MAC_DEPLOY" ;;
+  all)
+    build_slice iossim    iOS    iphonesimulator "arm64;x86_64" "$IOS_DEPLOY"
+    build_slice ios-arm64 iOS    iphoneos        "arm64"        "$IOS_DEPLOY"
+    build_slice macos     Darwin macosx          "arm64"        "$MAC_DEPLOY"
+    pack_xcframework iossim ios-arm64 macos
+    ;;
+  pack) shift; pack_xcframework "$@" ;;
+esac