Three worked recipes for OpenAI-compatible cloud providers, plus the
Copilot HTTP 401 auto-recovery info block and the GMI Cloud row in the
compatible providers table. All three additions were on the original
docs/custom-providers-cookbook branch but its merge base predated 1186
main commits, making the rebase impractical (84k+ line conflict).
Replays just the providers.md additions onto current main.
acca3ec3af