Construction queues now run on materials, not just position

Construction yards now check the ground before they break it. A queued job is accepted into the active queue only when every building material the blueprint calls for is physically on site at the project.

• Ready jobs pass waiting ones. A job stuck waiting for materials keeps its place in line, but it no longer blocks the yard — the next job whose materials have arrived starts in its slot.
• Clearer queue status. The yard's build queue marks jobs that are Awaiting materials, and customers see the same reason on their project card.
• Materials stay committed. While a project has a live construction order, its staged materials can't be liquidated or shipped elsewhere out from under the builder.

Jobs that were already mid-build without their materials on site have been moved back to the pending queue (the builder's consumed fuel and tools were refunded). They'll start automatically once the missing materials are delivered.