Write portable code

Before I drop this into the repo, make it easy for a reviewer to judge portability: list any remaining system calls or extensions, move endian, alignment, and path handling into a tiny portability layer with clear names, surface ABI-sensitive choices at the top, and flag anything that requires compiler-specific flags or headers that will break cross-compilation.

I just built the feature branch on my Windows dev box and MSVC errors out on alignas usage and a pragma I copied from Linux. The team is James on build infra and Maria who owns release builds. I’m worried this hides an ABI difference or a lost dependency I cannot see from here. Is this likely a header/attribute mismatch or a deeper compatibility bug, and what do I do first to unblock the Windows build without disturbing the Linux CI?

We keep losing time when a change that works on my Linux machine breaks Windows or macOS builds. The pain points are platform-specific headers strewn through the code, implicit assumptions about sizes and endianness, and ad-hoc compiler flags added by whoever made the quickest fix. Which habits should I make the team adopt so we stop shipping platform debt and shorten those weekend firefights?