v0.15.0: Orbital platforms

Five satellites is a finished power grid. What comes next is a shipyard.

Added

• The Orbital Factory Program, offered once your constellation is full. It opens a second thing to launch.
• Platform launches use the same run as a satellite, but the payload is heavier: the climb takes a full minute instead of thirty seconds, so the array has to hold longer. Each platform costs twice the one before it.
• Every platform is a build slot. It fabricates one invader ship at a time, so a second platform means two ships at once, and a fleet is limited by what you can afford and how long you are willing to wait.
• Build anything you have fought, from gnats to bosses. Cost and build time both follow how dangerous the thing is: a gnat takes two minutes, a boss takes an hour. Builds continue while you are away.
• Fabrication Lines research shortens every build. Splitter Doctrine and Shield Doctrine let you fit a ship with the same tricks the invaders use on you, for extra cost and time.
• Orbital Command, a screen of its own: you are standing in a platform's hangar, looking out the bay doors at the world you defend while gantry claws and a hover-lift work the deck behind you. Below the view sits a strip of what every platform is building and the roster of what you can order. The Research Center links across to it.

The fleet has nowhere to go yet. It is waiting for the invasion.