Tutorial polish, materials, and loading

The tutorial no longer prompts for steps that aren't relevant to your current state — if a selection has already been made or a step isn't needed yet, it's skipped.

Several new materials have been added and existing material icons have been updated. They now appear correctly in inventory and reward screens.

Menu and inventory art has received a full visual pass. Multiple screens that previously showed placeholder or mismatched images now display the correct artwork.

Scene backgrounds now preload earlier in the transition, so you're less likely to see a blank moment before the image appears. Loading should feel noticeably smoother.