I’m looking for someone who can take me from concept to store-ready builds of a fully private messenger that runs smoothly on both Android and iOS. The core must be rock-solid end-to-end encryption so that neither the server nor any third party can read user content. The app should let users exchange real-time text and voice messages, handle push notifications reliably, and present a clean, modern interface that feels instantly familiar to anyone who has used WhatsApp or Signal. Here’s the journey I have in mind: • Mobile clients: Native quality on each platform (I’m open to Kotlin/Swift, Flutter, React Native—whatever lets us ship fast without sacrificing polish). • Encryption layer: Proven algorithms (e.g., Signal Protocol, libsodium, or equivalent) with proper key-pair generation, forward secrecy, and secure key storage on device. • Backend: A lightweight, scalable service to broker delivery, manage device tokens, and enforce E2E without retaining any readable payloads. • Quality gates: Unit + integration tests, code comments, and clear build instructions so I can compile the project myself at any time. Acceptance criteria – Successful exchange of text and voice messages between two devices on each platform, verified in TestFlight / internal track. – Independent inspection confirms that messages stored on the server are indecipherable. – No crashes during a 48-hour soak test with at least 100 concurrent conversations. – Complete source code, build scripts, and minimal setup guide delivered before sign-off. If you’ve shipped secure chat apps before—or have deep cryptography experience—let’s talk specifics and map out the milestones together. Please also list the requirements for such a business, and your estimates on monthly expenses. Keep it short and be direct in proposals, I don't want to read through novels. Thanks and let's work