Kann Snapchat weg?

Build me a private ephemeral photo-messaging app, snaps for one friend group that opts in. Requirements:

- Node 22 + Fastify + better-sqlite3, and a vanilla-JS installable PWA served from
  /public with no build step: manifest, service worker, an offline shell that caches
  the UI but never caches snaps.
- Core loop: open the camera with getUserMedia, capture a photo, type or draw a
  caption overlay on a canvas, send it to one or more friends.
- A snap is viewable exactly once for up to 10 seconds; the server deletes the image
  file immediately after the view and keeps only a minimal sent/opened log row.
- Accounts are invite-code only: the admin seeds codes with a CLI script, signup is
  username plus passcode, sessions are httpOnly cookies.
- Per-pair daily streaks tracked server-side, shown next to each friend.
- Group stories: a snap posted to my story is visible to all members and hard-deleted
  after 24 hours by a sweep job.
- Media lives as files on disk outside the web root; metadata in SQLite with WAL mode.
- Web push for new snaps behind a permission prompt; the app must work fully without
  it, and the README says iOS web push is best-effort. VAPID keys and session secret
  in .env, with a documented script that generates them and a .env.example.
- HTTPS is required for camera and push: document local dev with a self-signed cert
  and production behind Caddy on a cheap VPS.
- Be honest in the UI: label view-once as deleted from our server, and state plainly
  that screenshots cannot be detected on the web.
- Tests for delete-after-view, the 24-hour story sweep, and streak day-boundary math
  with a fake clock.
- Out of scope: AR lenses and face filters, Snap Map, Discover or Spotlight feeds,
  video calls, screenshot detection, analytics, and third-party auth.
- README: setup, deploying, where data lives, how deletion actually works, and how
  to invite the first two friends.