The author's public key (hex string)
Array of relay URLs for the group (becomes the relays tag). Must be
non-empty and every URL must be distinct — matching the #236
list-cardinality rule this rumor's own consumer (getWelcome /
getWelcomeGroupRelays, via getListTag) enforces (WIRE-02).
The ID of the KeyPackage event consumed for this add. Required: the spec
mandates a 32-byte-hex e tag on every welcome rumor
(transports/nostr.md "Welcome delivery").
The MLS welcome message
Welcome rumor with precomputed ID
Creates a welcome rumor (kind 444) for a welcome message.