How exactly do you construct a highly secure software supply chain that seamlessly manages both multi-format build packages and container images in a unified cloud repository? Furthermore, this fully managed tool expands upon legacy image registries by providing fine-grained identity access management and integrated automated vulnerability scanning for your deployment deliverables. Why does its unique ability to host regional repositories directly next to your compute runtimes serve as the most foundational strategy for eliminating cross-region network egress costs and minimizing cold-start delivery latency?