* fix(gateway): skip confirmed-dead delivery targets (deleted groups, blocked bots)
A deleted Telegram group, kicked/blocked bot, or deactivated user keeps
throwing Forbidden/not_found on every cron tick and fan-out delivery. Each
retry burns a send against the platform's flood-control envelope and spams
the logs, making the whole session feel broken even when the model call
completed.
Add a small persistent DeadTargetRegistry (per-profile JSON under
HERMES_HOME) that records a target the moment a send reports a whole-chat
death (forbidden / chat-level not_found), and have DeliveryRouter.deliver()
short-circuit it on subsequent attempts. Self-healing: any successful send
clears the flag, so a user re-adding the bot recovers with no manual cleanup.
Thread/topic-level not_found is NOT recorded (adapters already self-heal that
by retrying without reply_to). Transient/timeout errors are never marked dead.
* infographic: dead delivery target skipping
