I’m launching a community-driven exchange where every member can post what they’re happy to give and what they’d love to receive, then connect in a safe, anonymous space. The first release will be a mobile app for both iOS and Android. Core experience • Users sign up with a simple phone-number OTP flow—no emails or social logins. • After onboarding, they create “Offers” and “Wishes” that appear in a shared feed. • Powerful search and category filters help people find matching items or skills fast. • An in-app chat lets two parties negotiate or arrange hand-offs without revealing personal details; identities are masked until both approve disclosure (or never, if they prefer). I’ll need a full solution—frontend, backend, and database—delivered ready for store submission, complete with basic moderation tools and analytics hooks. Please outline the tech stack you recommend (React Native, Flutter, Firebase, GraphQL, etc.), a high-level architecture, and a timeline with clear milestones through to final deployment.