forked from admin/VolcanicAgenticCore
Add TelegramLimits, TelegramChatChannel (every delivery through
ChatRenderer.RunInOrderAsync, auto photo falls back to a document on a 400)
and wire it into ChatRegistry as AgentSessionOptions.Channel and
ChatContext.Channel. Spec: SendTextAsync names its failure text
("Telegram did not accept the message.") and throws when any chunk fails.