Adds forwarded_from (original sender from the forwarded header block,
English/German) to delivery provenance and source match rules, so only
founder forwards of noreply@x.ai mail route as Grok briefs.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Assistant: claude-code
Assistant-Model: opus
Assistant-Process: 1170398@bnt-lap001
Assistant-Session: 622cd705-cb31-4322-ba08-dd42e44fa583
