fix: cross-platform socket handling for Windows

[kajukitli]

Fixes Windows build errors in PR denoland#32418 (denoland/deno).

Changes:

• Replace libc socket types with socket2::SockAddr for cross-platform compatibility
• Use #[cfg(unix)] for fcntl calls (non-blocking mode on Windows is handled by libuv)
• Add Windows-specific ioctlsocket for non-blocking mode
• Update libnghttp2 dependency to use fork with fixed enum constant types (fix: use consistent u32 type for enum constants on Windows denoland/libnghttp2#2)

This should fix the Windows CI failures:

• cannot find function fcntl in crate libc
• cannot find type sockaddr_storage in crate libc
• expected u32, found i32 for nghttp2 constants

Related PRs:

• fix: use consistent u32 type for enum constants on Windows denoland/libnghttp2#2 (libnghttp2 enum fix)
• feat(ext/node): http2 implementation with libuv compat denoland/deno#32418 (original PR)