walletBackupPrefsProvider

SUPPLIER of the wallet-level backup prefs carried INSIDE the app-state blob (see WalletBackupPrefs) — the SDK can't derive them (the committed toggle is host UI state). A supplier, not a pushed field, on purpose: it's read at UPLOAD time, so a pref change (e.g. the restore gate committing the toggle ON, or mirroring an opt-out) is always reflected in the next blob without the host re-pushing a snapshot at every mutation site — a pushed snapshot went stale and clobbered restored cloud truth. The host sets this once per build. Null supplier / null result → prefs marked absent.