Windows remote-environment test

This Bazel-only test_codex integration test runs a Windows exec-server fixture under pinned Wine and exercises the normal model tool-call and remote-execution path.

Running the test

bazel test \
  //codex-rs/core/tests/remote_env_windows:smoke-test \
  --test_output=errors

No system Wine is required. Every process gets a fresh WINEPREFIX and isolated wineserver.

Current limitations

ConPTY/TTY behavior is not yet covered.
Wine loads shared objects and PE DLLs at runtime, so the host must still provide the declared compatible glibc version.
The target is intentionally limited to x86-64 for simplicity. It can expand if we find aarch64-specific behavior worth testing.