As for your 2nd option there are already buildings that increase a system's defence against invasion so that it takes longer for enemy fleets to take the system, but these do not in any way damage or otherwise hinder the enemy fleet.



I do however really like your first option. It would be nice perhaps as well to have specialised modules for these stations that could hold enemy fleets in place, such as gravity generators (Interdictors) This way you could make your own strategic routes through the game by preventing an enemy fleet from escaping until they'd either 1) defeated your platform or 2) had already researched some way to bypass it (should be expensive!)