Apply big stealth malus to fleets in Obstructive stance after first turn of blockade

[Oberlus]

Feature request

Idea

Apply -40 to stealth to fleets in Obstructive stance, to avoid indefinite, unbreakable blockades.

The reasoning is that it is not possible to obstruct passage of a ship if you don't reveal yourself, and that allowing such behavior breaks the game.

So, the turn in which an enemy fleet arrives to a system with a hidden fleet set to obstructive there is no combat, but the next turn the blockading fleet becomes visible and the blockaded fleet can initiate combat if it was set to aggressive, thus removing the blockade.

Maybe -40 is too much or not enough. If allowing really high stealth empires to do this unbreakable blockade thingy is always a bad idea, then the malus should be greater.

Gain

Solves the problem of players being forced to rush detection to avoid losing the game without breaking other mechanics:

• It still allows pacific, permanent blockades between empires not at war, regardless of stealth.
• It allows enemy fleets to engage in combat with hidden blockades after one turn of blockade.

Discussion

The core idea of "Obstruct passage":
https://www.freeorion.org/forum/viewtopic.php?p=103797#p103797

Why it is a problem that breaks the game:
https://www.freeorion.org/forum/viewtopic.php?p=103843&sid=ef7618433ba9826219f7ac88f2805f3d#p103843
With screenshots:
https://www.freeorion.org/forum/viewtopic.php?p=117948&sid=0c16a6dcf646e1a09d29fb6971526661#p117948

Alternatives

• Remove the Obstructive fleet stance.
• Allow obstructed fleets to continue their travel after one turn of blockade.