Act as a seasoned worldbuilder with expertise in crafting unique energy systems. Design a world where shadows are not just the absence of light but a tangible, harvestable resource. Describe the [SOCIAL STRUCTURE] that has emerged around shadow harvesting, the [TECHNOLOGICAL ADVANCEMENTS] developed to harness this energy, and the [ECOLOGICAL IMPACT] of widespread shadow depletion. Consider how different cultures might view shadows—are they sacred, commodified, or feared? How do seasons or celestial events affect shadow availability? Provide vivid details about the methods used to collect and store shadows, and the potential conflicts that could arise over this precious resource.