fix: show a translated notice when the sign-in session expired

The sign-in screen showed the auth store's raw English error ("Session
expired", "Invalid username or password") as the notice title. It now
runs it through describeLoginError like every other sign-in failure,
which also learns to explain an expired session with the webmail's
login.session_expired copy. The back and close buttons of the sign-in
steps get screen reader labels, and the email placeholders use the
webmail's translated example address.

src/components/__tests__/screens-i18n.test.ts

@@ -17,6 +17,17 @@ const TRANSLATED_FILES: Record<string, string[]> = {
   // The link prompt shows an example URL.
   'screens/ComposeScreen.tsx': ['https://example.com'],
   'components/RichTextEditor.tsx': [],
+  'screens/LoginScreen.tsx': [],
+  // Product name and example host.
+  'screens/login/ChooseStep.tsx': ['Bulwark Mail'],
+  'screens/login/ConfirmStep.tsx': [],
+  'screens/login/EmailStep.tsx': [],
+  'screens/login/LoginNotice.tsx': [],
+  'screens/login/LoginShell.tsx': ['Bulwark Mobile v'],
+  'screens/login/OptionTile.tsx': [],
+  'screens/login/PasswordStep.tsx': [],
+  'screens/login/ServerStep.tsx': ['mail.example.com'],
+  'screens/login/SigningInStep.tsx': [],
   'screens/ScheduledScreen.tsx': [],
   'screens/EmailSourceScreen.tsx': [],
   'components/OfflineBanner.tsx': [],

src/lib/__tests__/login-errors.test.ts

@@ -14,6 +14,11 @@ describe('describeLoginError', () => {
     expect(copy.detail).toMatch(/app password/i);
   });
 
+  it('explains the auth store\'s "Session expired" notice', () => {
+    expect(describeLoginError('Session expired').title).toBe('Your session has expired. Please sign in again.');
+    expect(describeLoginError('Session expired for this account').title).toBe('Your session has expired. Please sign in again.');
+  });
+
   it('names the host it could not reach', () => {
     const copy = describeLoginError(named('NetworkError', 'Network request failed'), {
       serverUrl: 'https://mail.example.com',

src/lib/login-errors.ts

@@ -84,6 +84,12 @@ export function describeLoginError(err: unknown, context: LoginErrorContext = {}
     };
   }
 
+  // A saved session the server no longer accepts (the auth store's
+  // "Session expired" notice when the app lands back on sign-in).
+  if (lower.includes('session expired')) {
+    return { title: t('login.session_expired', 'Your session has expired. Please sign in again.') };
+  }
+
   if (lower.includes('certificate') || lower.includes('ssl') || lower.includes('tls')) {
     return {
       title: t('login.mobile.err_cert_title', "Couldn't verify {host}", { host }),

src/screens/LoginScreen.tsx

@@ -333,7 +333,8 @@ export default function LoginScreen({ onLogin, isAddMode = false, onCancel }: Lo
   if (step === 'choose') {
     // A leftover store error ("Session expired") is the reason some people
     // land back here, so it belongs on this screen.
-    const chooseNotice = notice ?? (storeError ? { title: storeError } : null);
+    // The store keeps the raw English message; show the translated copy.
+    const chooseNotice = notice ?? (storeError ? describeLoginError(storeError, { t }) : null);
     return (
       <>
         <LoginShell {...shellProps} centered showFooter>

src/screens/login/EmailStep.tsx

@@ -49,7 +49,7 @@ export default function EmailStep({
       </View>
 
       <Input
-        placeholder="you@example.com"
+        placeholder={t('login.username_placeholder', 'user@example.com')}
         value={value}
         onChangeText={onChange}
         autoFocus

src/screens/login/LoginShell.tsx

@@ -13,6 +13,7 @@ import Constants from 'expo-constants';
 import { ArrowLeft, X } from 'lucide-react-native';
 import { spacing, typography, componentSizes, type ThemePalette } from '../../theme/tokens';
 import { useColors } from '../../theme/colors';
+import { useLocaleStore } from '../../stores/locale-store';
 
 const APP_VERSION = Constants.expoConfig?.version ?? '0.0.0';
 
@@ -41,6 +42,7 @@ export default function LoginShell({
 }: LoginShellProps) {
   const c = useColors();
   const styles = React.useMemo(() => makeStyles(c), [c]);
+  const t = useLocaleStore((s) => s.t);
 
   return (
     <SafeAreaView style={styles.container}>
@@ -50,14 +52,26 @@ export default function LoginShell({
       >
         <View style={styles.header}>
           {onBack ? (
-            <Pressable onPress={onBack} hitSlop={12} style={styles.headerButton}>
+            <Pressable
+              onPress={onBack}
+              hitSlop={12}
+              style={styles.headerButton}
+              accessibilityRole="button"
+              accessibilityLabel={t('common.back', 'Back')}
+            >
               <ArrowLeft size={22} color={c.textSecondary} />
             </Pressable>
           ) : (
             <View style={styles.headerButton} />
           )}
           {onClose ? (
-            <Pressable onPress={onClose} hitSlop={12} style={styles.headerButton}>
+            <Pressable
+              onPress={onClose}
+              hitSlop={12}
+              style={styles.headerButton}
+              accessibilityRole="button"
+              accessibilityLabel={t('common.close', 'Close')}
+            >
               <X size={22} color={c.textSecondary} />
             </Pressable>
           ) : (

src/screens/login/PasswordStep.tsx

@@ -55,7 +55,7 @@ export default function PasswordStep({
 
       <Input
         label={t('login.mobile.username_label', 'Email or username')}
-        placeholder="you@example.com"
+        placeholder={t('login.username_placeholder', 'user@example.com')}
         value={email}
         onChangeText={onChangeEmail}
         autoCapitalize="none"