Upcoming issues with `SharedArrayBuffer`

It is worth noting that Chrome will disable SharedArrayBuffer by default from Chrome 113 unless a site is cross origin isolated, which means that it serves these headers:

Cross-Origin-Embedder-Policy: require-corp
Cross-Origin-Opener-Policy: same-origin

See https://developer.chrome.com/blog/enabling-shared-array-buffer/

It is relevant for this Repo, as the type of File Reader that we enable when compiling the WASM uses SharedArrayBuffer to pass a multi-gigabyte File to the WASM Worker without copying or loading in memory. This is why the WASM doesn't work on Chrome Mobile, where there is no support for SharedArrayBuffer except behind a flag, and it seems no support at all for it with POSIX threading enabled in source binaries.

For the PWA versions, we should be able to serve those headers. Other versions that don't use https: may struggle. We may need to look into alternative file systems for the WASM.

Start with the linked Chrome guidance, then trace how the PWA versions serve responses and where the WASM File Reader uses SharedArrayBuffer for the WASM Worker. Determine whether the required cross-origin-isolation headers cover the PWA versions and document or investigate an alternative filesystem approach for non-HTTPS and Chrome Mobile cases.