menotbobbybrown/lastsignal ? reverse-engineered prompt

Build me a self hosted dead man’s switch web app where people can write private messages for loved ones and have them delivered by email only if they stop checking in.

I want a simple account flow where someone signs up, gets a magic link by email, adds recipients, invites them to accept with a passphrase, and then creates encrypted messages for each recipient. The app should keep the messages unreadable on the server, schedule automatic check in emails, send reminders if the user does not respond, and after the final missed check in, deliver the messages by email.

Please include a way to set timing for check ins and reminders, trusted contact notifications, and an optional keep alive webhook for automation. Make it feel polished, with a clear dashboard, status indicators, and good email templates. It should run locally with SQLite and be easy to self host with Docker, and if you need to look up current docs or best practices online, go ahead.