feat: add quiet reading with rare confirmations

Part of the quiet-user-feedback change; docs and specs land in their own repositories.

src/shared/lib/index.ts

@@ -8,4 +8,8 @@ export {
 	formatSnapshotTime,
 	instrumentLogoUrl,
 } from "./display";
+export {
+	type InitialAvailability,
+	useInitialAvailability,
+} from "./initial-availability";
 export { useUrlPeriod } from "./useUrlPeriod";