- Add TELEGRAM_GROUP_IDS configuration setting to enable optional group/channel filtering
- Add _is_group_enabled() authorization check to all command handlers
- Add group/channel authorization check to message_handler
- All handlers now verify both user authorization and group authorization
- If TELEGRAM_GROUP_IDS is not configured, bot accepts messages from any group
- If TELEGRAM_GROUP_IDS is configured, bot only processes messages from those groups
This enables the bot to be used in group chats and channels with Topics/Threads support.
