federation.md: new 'Approval Token Verification' subsection covering
issuance (queue path generates token, returns in 202), storage on
initiator (federation_peers.approval_token), forwarding from /approve,
verification on receiver's awaiting_approval branch, single-use lifecycle,
backward compatibility, and threat-model boundary (sender-side outbound
gating tracked separately).
database.md: approval_token column documented on both federation_peers
and peer_approval_requests with cross-references to federation.md.
api.md: /peer/accept request + 202 response now show optional
approvalToken field with pointer to the federation spec.