fix(login): ask how to protect a saved account after the login succeeds

The protection picker used to show before the login attempt, so a wrong
password still walked the user through choosing a PIN/password for an
account that never logged in - and a Quick Connect login could not save
the account at all.

Login flows now only flag the intent (pendingAccountSaveAtom); the
picker is a global PendingAccountSaveModal mounted at the root, shown
once the session is authorized - the login screen unmounts on success,
so it cannot host the modal itself. Works identically for the password
and Quick Connect flows; the credential is saved from the live session
token (saveCurrentAccount). Cancelling saves nothing, and a logout
before answering drops the intent.

app/_layout.tsx

@@ -11,6 +11,7 @@ import { Image } from "expo-image";
 import { DarkTheme, ThemeProvider } from "expo-router/react-navigation";
 import { Platform } from "react-native";
 import { GlobalModal } from "@/components/GlobalModal";
+import { PendingAccountSaveModal } from "@/components/PendingAccountSaveModal";
 import { enableTVMenuKeyInterception } from "@/hooks/useTVBackHandler";
 import i18n from "@/i18n";
 import { DownloadProvider } from "@/providers/DownloadProvider";
@@ -547,6 +548,7 @@ function Layout() {
                                   closeButton
                                 />
                                 {!Platform.isTV && <GlobalModal />}
+                                {!Platform.isTV && <PendingAccountSaveModal />}
                               </ThemeProvider>
                             </IntroSheetProvider>
                           </BottomSheetModalProvider>