This fix addresses the issue where the container gets stuck in an endless
loop of Telegram connection errors when the bot is configured but Telegram
is unreachable during startup.
Changes:
- Add 10-second startup delay before initializing Telegram polling to allow
the system to settle
- Implement exponential backoff (5s to 5min) when Telegram connection fails
- Add rate-limited error logging (max once per minute per user) to reduce
log spam and prevent event loop blocking
- Track error state per user to manage backoff independently
- Auto-reset error state on successful connection
- Update tests to account for new error state tracking
Fixes#989
