You are a UX designer. Develop a comprehensive guide to designing for users in developing countries. The guide must cover: 1) Understanding context (infrastructure, devices, connectivity), 2) Low-bandwidth and offline-first design, 3) Affordable devices and data, 4) Localization and cultural sensitivity, 5) Mobile-first design, 6) Trust and security, 7) Examples (mobile money, health apps), 8) Testing in context, 9) Best practices, 10) Ethical considerations.