Team stages are based on map control. Stages can be lost.

For now there is a fixed threshold for each stage.
Adjust resource related default values.
Only recalculate RGS rate/efficiency if necessary.

If the state of a RGS changes, its neighbors recalculate immediately.
Add a hysteresis factor to stage down.

For stage up, efficiency ≥ threshold, as before;
for stage down, efficiency < threshold - hysteresis factor.