feat(service): add foreground service for background message sync

Implement Android foreground service to keep app alive in background for real-time message sync:
- Add withForegroundService expo config plugin for notification channel setup
- Add BackgroundSyncManager with REALTIME, BATTERY_SAVER, and DISABLED modes
- Add ForegroundServiceModule for native Android foreground service binding
- Refactor backgroundService to integrate foreground service and expo-background-task

Also refactor auth and profile screens to use dynamic theme colors:
- Replace hardcoded THEME_COLORS with colors.primary.main, colors.background.paper, etc.
- Add useResolvedColorScheme for dynamic StatusBar styling
- Update NotificationSettingsScreen with sync mode selection UI

BREAKING CHANGE: Switched from expo-background-fetch to expo-background-task, minimum background sync interval changed from 900s to 15min in config

src/screens/message/ChatScreen.tsx

@@ -33,7 +33,7 @@ import { useNavigation, useRouter } from 'expo-router';
 import { StatusBar } from 'expo-status-bar';
 import { SafeAreaView, useSafeAreaInsets } from 'react-native-safe-area-context';
 import { Text, ImageGallery, ImageGridItem } from '../../components/common';
-import { useAppColors } from '../../theme';
+import { useAppColors, useResolvedColorScheme } from '../../theme';
 import * as hrefs from '../../navigation/hrefs';
 import { messageManager, callStore } from '../../stores';
 import { useBreakpointGTE } from '../../hooks/useResponsive';
@@ -56,6 +56,7 @@ export const ChatScreen: React.FC = () => {
   const router = useRouter();
   const insets = useSafeAreaInsets();
   const colors = useAppColors();
+  const resolved = useResolvedColorScheme();
   const styles = useChatScreenStyles();
 
   // 响应式布局
@@ -406,7 +407,7 @@ export const ChatScreen: React.FC = () => {
         behavior={Platform.OS === 'ios' ? 'padding' : undefined}
         keyboardVerticalOffset={Platform.OS === 'ios' ? 0 : 0}
       >
-        <StatusBar style="dark" backgroundColor="#FFFFFF" />
+        <StatusBar style={resolved === 'dark' ? 'light' : 'dark'} backgroundColor={colors.background.paper} />
       
       {/* 顶部栏 */}
       <ChatHeader
@@ -499,7 +500,7 @@ export const ChatScreen: React.FC = () => {
           >
             <View
               style={{
-                backgroundColor: 'rgba(255,255,255,0.9)',
+                backgroundColor: colors.background.paper + 'E6',
                 borderRadius: 12,
                 paddingHorizontal: 10,
                 paddingVertical: 6,