Returns the group relays from a welcome rumor. Strict (#236): a repeated
relays tag, an empty/absent one, or one carrying duplicate URLs yields
[] rather than silently resolving to the first match (WIRE-02).
NOTE: The "relays" tag is a normal Nostr tag vector: ["relays", ...urls]
(see transports/nostr.md "Welcome delivery" and createWelcomeRumor()).
Returns the group relays from a welcome rumor. Strict (#236): a repeated
relaystag, an empty/absent one, or one carrying duplicate URLs yields[]rather than silently resolving to the first match (WIRE-02).NOTE: The "relays" tag is a normal Nostr tag vector: ["relays", ...urls] (see transports/nostr.md "Welcome delivery" and createWelcomeRumor()).