AI Edge — Custom Host Header

[mattdjenkinson]

You can now set a custom Host header on AI Edge endpoints. Useful when your upstream routes traffic by hostname (multi-tenant SaaS, virtual-hosted buckets, model gateways that key off the request host) and the backend address you've configured doesn't match what the upstream expects to see.

• Configure it on any AI Edge proxy from the endpoint host-header field, or set requestHeaderModifier.set[name=Host] directly via datumctl.
• Applies per-rule; backends without an override are unchanged.
• Fixes a prior issue where the documented datumctl recipe returned a 500 — the controller now respects your override instead of rewriting it.