feat(app-expo): env variants, local iOS prebuild, and About diagnostics

Align staging/production builds with APP_VARIANT bundle IDs, allow staging HTTP on iOS, add ios-prebuild scripts for TestFlight, and show connected API URL on About for non-production builds.

Co-authored-by: Cursor <cursoragent@cursor.com>

app-expo/src/app/(main)/about.tsx

@@ -1,25 +1,44 @@
 import Constants from 'expo-constants';
 import React from 'react';
 import { View } from 'react-native';
+import { useTranslation } from 'react-i18next';
 import { SafeAreaView } from 'react-native-safe-area-context';
 
 import { Text } from '@/components/ui/text';
 import { ScreenHeader } from '@/components/screen-header';
+import { config } from '@/core/config';
 
 export default function AboutScreen() {
+  const { t } = useTranslation('profile');
   const version = Constants.expoConfig?.version ?? '1.0.0';
+  const showBackend = config.showAboutBackendUrl;
 
   return (
     <View className="flex-1 bg-background">
-      <ScreenHeader title="关于" />
+      <ScreenHeader title={t('about.title')} />
       <SafeAreaView className="flex-1 items-center justify-center gap-4 px-6">
         <Text variant="h2" className="text-foreground">
-          岁月时书
+          {t('about.appName')}
         </Text>
-        <Text className="text-muted-foreground">Life Echo</Text>
-        <Text className="text-sm text-muted-foreground">版本 {version}</Text>
+        <Text className="text-muted-foreground">{t('about.appSubtitle')}</Text>
+        <Text className="text-sm text-muted-foreground">
+          {t('about.version', { version })}
+        </Text>
+        {showBackend ? (
+          <View className="w-full max-w-sm items-center gap-1">
+            <Text className="text-sm text-muted-foreground">
+              {t('about.backend')}
+            </Text>
+            <Text
+              selectable
+              className="text-center font-mono text-xs text-muted-foreground"
+            >
+              {config.apiBaseUrl}
+            </Text>
+          </View>
+        ) : null}
         <Text className="mt-8 text-center text-sm leading-5 text-muted-foreground">
-          记录你的人生故事，让回忆成书。
+          {t('about.tagline')}
         </Text>
       </SafeAreaView>
     </View>