Added building selection — clicking a building now selects it and shows its details in the HUD. Extracted a shared SelectionBehavior to handle the selection logic across all building types (habitats, mines, landing pads, ship factories). Each building’s draw function now renders a selection highlight when active.

Fixed a bug where asteroids would disappear on hover due to a rendering issue in AsteroidShape. Also improved the MouseManager to properly handle click targets across buildings and other entities.