It looks like I didn't really finish my post, and just hit publish :)
The reason why I'm scrapping the "construction platform" that you have to build at a star system is because of the new "special equipment" you can add to a ship. Remember that the game supports both starships and system ships. Which means you can build a system ship that aren't going anywhere, with the special construction equipment, and you've essentially got a "construction platform"
I also thought, why not allow ships without engines at all? They'd still require reactors, but they'll be essentially space stations, unable to propel itself anywhere. But it will free up some space for weapons and other stuff. Also, ships with only stellar drives can travel to different stars, but in combat it can't move, making for interesting designs!
I'm also thinking of making Stargates just one size, big enough to allow whatever through, because it'd be very confusing to see two systems with stargate icons, but your ships can't go through. So it will be an "on/off", it's either there or not. Any ships can travel through stargates, even if they don't have engines. Think of tugboats pushing them into stargates :)
To terraform a planet, you will need either a ship with construction platform, or a planet that has a base on it, in the same system as the planet that you want to terraform. Terraforming includes building planets out of asteroids and gas giants.
Refitting a ship will require the same requirements, a planet or a ship with construction. To refit a ship, you just select a ship to refit, then a list of same-size designs to refit the ship into. For example, if you have a scout with one laser cannon, and you've designed a new scout of the same size, but with a rail gun and a shield, you pick the old scout, then pick the new design, and hit confirm. It will be cheaper than building a new ship.
The construction platform special equipment will take up so much space and be very expensive, so you'll have to use a hull big enough to support a platform. I'm thinking of making it so only the biggest hull can support such a platform. Of course, this will all be data driven, so you could create a technology item that allows you to put on a construction platform on the smallest hull and cost only 1 BC :)
I looked at my code, and realized that there's a few more stuff that need to be converted to use data before I can add production screen. I need to flesh out the special equipment/technologies a bit more to allow for colonization and ship production from special ships. Then I'm going to change the home system code to use the data for setting which ships/planets/systems you start with. When that's done, I will then work on the production screen and colonization prompt, as well as invasion/transfer prompt. Then the game will be kinda playable again!