interactive property to determine whether robots can be sensed by meet

[byorgey]

Yes, I agree, growing trees, flowers, etc. are going to be a problem... We use robots internally to simulate growth --- but from the perspective of a player that is just an implementation detail, they should not be returned by meet. ... An explicit boolean interactive property probably makes sense, and I think it makes sense for interactive = true to be the default, but invisible system robots can still be non-interactive by default.

Originally posted by @byorgey in #2262 (comment)