fix: fix theme switch

app/src/main/java/com/rosetta/messenger/MainActivity.kt

@@ -12,6 +12,7 @@ import androidx.activity.result.contract.ActivityResultContracts
 import androidx.compose.animation.*
 import androidx.compose.animation.core.tween
 import androidx.compose.foundation.background
+import androidx.compose.foundation.isSystemInDarkTheme
 import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.material3.Surface
@@ -129,7 +130,14 @@ class MainActivity : FragmentActivity() {
             }
 
             val scope = rememberCoroutineScope()
-            val isDarkTheme by preferencesManager.isDarkTheme.collectAsState(initial = true)
+            val themeMode by preferencesManager.themeMode.collectAsState(initial = "dark")
+            val systemInDarkTheme = isSystemInDarkTheme()
+            val isDarkTheme = when (themeMode) {
+                "light" -> false
+                "dark" -> true
+                "auto" -> systemInDarkTheme
+                else -> true
+            }
             val isLoggedIn by accountManager.isLoggedIn.collectAsState(initial = null)
             var showSplash by remember { mutableStateOf(true) }
             var showOnboarding by remember { mutableStateOf(true) }
@@ -296,11 +304,17 @@ class MainActivity : FragmentActivity() {
                                 MainScreen(
                                         account = currentAccount,
                                         isDarkTheme = isDarkTheme,
+                                        themeMode = themeMode,
                                         onToggleTheme = {
                                             scope.launch {
                                                 preferencesManager.setDarkTheme(!isDarkTheme)
                                             }
                                         },
+                                        onThemeModeChange = { mode ->
+                                            scope.launch {
+                                                preferencesManager.setThemeMode(mode)
+                                            }
+                                        },
                                         onLogout = {
                                             // Set currentAccount to null immediately to prevent UI
                                             // lag
@@ -461,7 +475,9 @@ class MainActivity : FragmentActivity() {
 fun MainScreen(
         account: DecryptedAccount? = null,
         isDarkTheme: Boolean = true,
+        themeMode: String = "dark",
         onToggleTheme: () -> Unit = {},
+        onThemeModeChange: (String) -> Unit = {},
         onLogout: () -> Unit = {},
         onAccountInfoUpdated: suspend () -> Unit = {}
 ) {
@@ -667,13 +683,12 @@ fun MainScreen(
             if (showThemeScreen) {
                 ThemeScreen(
                     isDarkTheme = isDarkTheme,
-                    onBack = { 
+                    currentThemeMode = themeMode,
+                    onBack = {
                         showThemeScreen = false
                         showProfileScreen = true
                     },
-                    onThemeChange = { isDark ->
-                        onToggleTheme()
-                    }
+                    onThemeModeChange = onThemeModeChange
                 )
             }
         }