AZL-99321 CVE-2026-78662 affecting package packer for versions less than 1.9.5-21

Previously, a channel registered in the mux's chanList is not usable until it is established. A malicious peer was able flood the channel's incomingRequests, deadlocking the entire connection. Now, we add an atomic established state, set when a channel becomes usable. Until such a time,...