M12 Lifecycle

This is a design layer skill that helps you think through resource lifecycle questions before you write code. It maps patterns like RAII, lazy initialization, and connection pooling to concrete Rust implementations, then shows you which Layer 1 skills handle the actual code. The tables are genuinely useful: they show when Drop fires, how to choose between OnceLock and LazyLock, and why you'd pool versus create per use. It's structured around tracing up to domain constraints and down to implementation details, which matches how you actually think through these decisions. The anti-patterns section is honest about common mistakes like forgetting cleanup or reaching for lazy_static when stdlib works fine.