types: include ExitRoutes in HasNetworkChanges

When exit routes are approved, SubnetRoutes remains empty because exit
routes (0.0.0.0/0, ::/0) are classified separately. Without checking
ExitRoutes, the PolicyManager cache is not invalidated on exit route
approval, causing stale filter rules that lack via grant entries for
autogroup:internet destinations.

Updates #2180

hscontrol/types/node.go

@@ -1030,6 +1030,10 @@ func (nv NodeView) HasNetworkChanges(other NodeView) bool {
 		return true
 	}
 
+	if !slices.Equal(nv.ExitRoutes(), other.ExitRoutes()) {
+		return true
+	}
+
 	return false
 }