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

app.json

@@ -2,7 +2,7 @@
   "expo": {
     "name": "萝卜社区",
     "slug": "qojo",
-    "version": "1.0.12",
+    "version": "1.0.13",
     "orientation": "default",
     "icon": "./assets/icon.png",
     "userInterfaceStyle": "automatic",
@@ -36,7 +36,7 @@
       },
       "predictiveBackGestureEnabled": false,
       "package": "skin.carrot.bbs",
-      "versionCode": 6,
+      "versionCode": 7,
       "permissions": [
         "VIBRATE",
         "RECORD_AUDIO",
@@ -63,6 +63,16 @@
     },
     "plugins": [
       "./plugins/withMainActivityConfigChange",
+      [
+        "./plugins/withForegroundService",
+        {
+          "notificationTitle": "萝卜社区",
+          "notificationBody": "正在后台同步消息",
+          "notificationIcon": "ic_notification",
+          "channelId": "carrot_sync_foreground",
+          "channelName": "消息同步"
+        }
+      ],
       [
         "expo-router",
         {
@@ -86,9 +96,9 @@
         }
       ],
       [
-        "expo-background-fetch",
+        "expo-background-task",
         {
-          "minimumInterval": 900
+          "minimumInterval": 15
         }
       ],
       [