Add sendFileToTelegram method that decodes base64 file data and sends
it via grammy's InputFile API. Handle send_file RoutedMessage action
in the virtual device sendCallback.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
Send "typing" chat action while LLM generates a response, with 5s
interval refresh and 60s safety timeout. Stop on message_end,
agent_error, or generic error events.
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>