Empty AllowedSuggestedExitNodes blocks all exit node suggestions

When AllowedSuggestedExitNodes policy is set but contains no exit node IDs (empty set), no exit nodes will be recommended to users or available for auto:any selection. This can cause confusion when users expect exit nodes to be suggested.

If exit nodes should be available for suggestion, either leave AllowedSuggestedExitNodes unset (which allows all exit nodes) or populate it with specific exit node IDs. Exit node IDs can be found in the admin console Machines page or via the Tailscale API. If intentionally blocking suggestions, document this configuration to prevent troubleshooting confusion.