## Why
The Bazel V8 source build supported Windows GNU but lacked an MSVC-targeting toolchain to produce `*-pc-windows-msvc` archives.
## What changed
- Add opt-in archive targets for native Windows x64 and ARM64 hosts, selected by `//third_party/v8:rusty_v8_native_windows_archive_for_target`.
- Fetch pinned LLVM and scope its `clang-cl` toolchain to V8 artifacts, using the installed Microsoft SDK. Bundle Chromium libc++ and compiler-rt builtins into the resulting `.lib`.
- Adapt V8 dependencies, assembly, snapshot generation, and platform feature settings for MSVC, and derive test metadata from the selected engine features.
- Document the native build workflow. Existing MSVC consumers continue using prebuilt artifacts; generated Rust bindings and publishing integration remain separate.
GitOrigin-RevId: abd5049245aece90a116fc3bfeac2b158a76f6af
## What changed
Add `third_party/v8/icu.BUILD.bazel` and wire V8's ICU repository to use it instead of patching upstream `bazel/BUILD.icu`.
Select ICU's custom libc++ flags and runtime dependencies through `//third_party/v8:use_rusty_v8_custom_libcxx`, keeping ICU aligned with V8 and its host generators.
GitOrigin-RevId: 92a1b883f5d42d9a3a464002e922295ab166f2bd
Sean Huang