test(golang): gate unix-only go e2e suites with cfg(unix) for Windows CI

e2e_golang_redirect.rs and e2e_golang_build.rs use std::os::unix permissions
(matching the cargo e2e suites, which are also #[cfg(unix)]); without the gate
they fail to compile on test (windows-latest). setup_go_roundtrip.rs stays
cross-platform (pure std::fs) for Windows setup-wiring coverage.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: mikolalysenko

crates/socket-patch-cli/tests/e2e_golang_build.rs

@@ -1,4 +1,4 @@
-#![cfg(feature = "golang")]
+#![cfg(all(unix, feature = "golang"))]
 //! Full go-toolchain capstone for the Go `replace`-redirect guard: proves the
 //! patched bytes are actually LINKED by `go build`, and that the committed guard
 //! enforces drift at runtime (`init()`) and self-heals.

crates/socket-patch-cli/tests/e2e_golang_redirect.rs

@@ -1,4 +1,4 @@
-#![cfg(feature = "golang")]
+#![cfg(all(unix, feature = "golang"))]
 //! End-to-end for the Go `replace`-redirect backend, driven through the CLI
 //! binary. No `go` toolchain needed: `apply`/`--check` only read a pristine
 //! extracted module-cache dir and write project-local copies + a `go.mod`