StellarSleep backend and admin

Sleep audio API, admin controls, and analytics in one local app.

This backend powers the SwiftUI app with auth, onboarding sync, recommendations, playlists, favorites, protected audio playback, subscription state, and an owner dashboard.

Open admin dashboard Inspect content API

Seeded routes

Local

`/api/auth/register` and `/api/auth/login` for app auth
`/api/onboarding/profile` for the persisted sleep profile
`/api/recommendations` for personalized sections
`/api/playlists`, `/api/favorites`, and `/api/player-events`
`/api/subscriptions/status` and `/api/content/[id]/play-url`
`/admin` for content, playlists, analytics, and subscriptions