When Telegram's sendRichMessage returns a FloodWait/RetryAfter error,
_try_send_rich() now extracts the server-provided retry_after value and
propagates it through SendResult.retry_after. The base _send_with_retry()
layer honors this value instead of using its default short exponential
backoff (~2s, ~4s), preventing the retry budget from being exhausted
against a server that demands a 25-37s wait.
Salvaged from #46774 by @liuhao1024. Telegram adapter path moved from
gateway/platforms/telegram.py to plugins/platforms/telegram/adapter.py
since the original PR.
Closes#46762
404b06ac4f