Ideally you could access the 1.27b full standalone installer, but at least this should allow you to patch from a Retail CD of TFT (or ROC) up to 1.27b without any DRM interference or forced updates. I haven't tested this yet, but this page provides direct links to Blizzard FTP servers to download 1.27b which is apparently the last 'standalone' version. I'm not exactly sure which version this is, but some quick reading online suggests that it might be 1.27.
but warcraft 3 reforged wants me to download it. Running the war3.exe binary directly seems to fail with a CD check. The two paths as I see it for truly preserving the classic game client (excepting the features) are: All it would take would be for them to remove this test version and suddenly this would update to Reforged, I think. The problem is that these latest versions check for updates when you start them. I wonder if this will continue to work long term.