Publish the latest 3DNX app build per flavor (phone / tv). Each box calls GET /api/version on startup and shows an update prompt when the published latest differs from its running version.

• latest is matched by exact string (not semver) — enter the precise versionName the new APK reports (e.g. 0.16.0).
• Download URL must be https:// — the box opens it to install.
• Force makes the update dialog non-dismissable (use sparingly).
• No row for a flavor ⇒ the endpoint is a no-op (it echoes the box's own version, so no prompt).