Function withScope

frontend/src/utils/storage-keys.ts:20–21

(base: string, scope: string, ...rest: string[])

// email-change migration (migrateUserStorage, renames by `.{email}` suffix)
// keeps working.
const withScope = (base: string, scope: string, ...rest: string[]): string =>
  [base, ...(scope ? [scope] : []), ...rest].join(".");

// --- Global (no user scope) ---
export const STORAGE_KEY_BACK_PATH = "bb.back-path";