Each WS connection generates its own ed25519 keypair (sessionPubkey)
sent in the hello handshake. The broker stores it on the presence
row and uses it for message routing + list_peers. This gives every
`claudemesh launch` a unique crypto identity without burning invite
uses — member auth stays permanent, session identity is ephemeral.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
