FR - make Auto-Sweeper zone highlight more useful

Now Auto-sweeper highlights its working zone as simple 9x9 square

Realistically it does not work such way -- tiles blocks it operation, for example. and not all tiles reachable on border

Can you please make this highlight more informative?

1. Highlight only tiles really reachable, like light source do
2. Highlight buildings reachable, like decor overlay do