Rust where we can own the path; partners at the edge

The destination is not an ideological ban on vendors. Surreal Cloud, Restate Cloud, OpenObserve Cloud, Stalwart Managed Email, and Miuda PBX are the Rust-operated lanes under recorded cutover gates. Xero, DocuSign, and the SIP carrier stay at the business edge, where they provide the service we do not claim to reimplement.