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/csharp/BUILD.bazel

@@ -0,0 +1,34 @@
+# Protobuf C# runtime
+#
+# See also code generation logic under /src/google/protobuf/compiler/csharp.
+
+load("@rules_pkg//:mappings.bzl", "pkg_files", "strip_prefix")
+
+pkg_files(
+    name = "dist_files",
+    srcs = glob([
+        "keys/*",
+        "protos/*",
+        "src/**/*.cs*",  # .cs and .csproj
+    ]) + [
+        ".editorconfig",
+        ".gitignore",
+        "BUILD.bazel",
+        "CHANGES.txt",
+        "Google.Protobuf.Tools.nuspec",
+        "Google.Protobuf.Tools.targets",
+        "NuGet.Config",
+        "README.md",
+        "build_packages.bat",
+        "build_tools.sh",
+        "buildall.bat",
+        "buildall.sh",
+        "generate_protos.sh",
+        "install_dotnet_sdk.ps1",
+        "src/Google.Protobuf.Benchmarks/wrapper_benchmark_messages.proto",
+        "src/Google.Protobuf.Test/testprotos.pb",
+        "src/Google.Protobuf.sln",
+    ],
+    strip_prefix = strip_prefix.from_root(""),
+    visibility = ["//pkg:__pkg__"],
+)