feat: Enhance back navigation in AuthFlow and add back button in WelcomeScreen for better user experience

app/src/main/java/com/rosetta/messenger/ui/auth/AuthFlow.kt

@@ -37,15 +37,22 @@ fun AuthFlow(
     var showCreateModal by remember { mutableStateOf(false) }
     
     // Handle system back button
-    BackHandler(enabled = currentScreen != AuthScreen.UNLOCK && currentScreen != AuthScreen.WELCOME) {
+    BackHandler(enabled = currentScreen != AuthScreen.UNLOCK && !(currentScreen == AuthScreen.WELCOME && !hasExistingAccount)) {
         when (currentScreen) {
-            AuthScreen.SEED_PHRASE -> currentScreen = AuthScreen.WELCOME
+            AuthScreen.WELCOME -> {
+                if (hasExistingAccount) currentScreen = AuthScreen.UNLOCK
+            }
+            AuthScreen.SEED_PHRASE -> {
+                currentScreen = if (hasExistingAccount) AuthScreen.WELCOME else AuthScreen.WELCOME
+            }
             AuthScreen.CONFIRM_SEED -> currentScreen = AuthScreen.SEED_PHRASE
             AuthScreen.SET_PASSWORD -> {
                 currentScreen = if (hasExistingAccount) AuthScreen.UNLOCK else AuthScreen.CONFIRM_SEED
             }
-            AuthScreen.IMPORT_SEED -> currentScreen = AuthScreen.WELCOME
+            AuthScreen.IMPORT_SEED -> {
-            else -> {} // UNLOCK and WELCOME don't have back navigation
+                currentScreen = if (hasExistingAccount) AuthScreen.WELCOME else AuthScreen.WELCOME
+            }
+            else -> {} // UNLOCK doesn't have back navigation
         }
     }
     
@@ -84,6 +91,8 @@ fun AuthFlow(
             AuthScreen.WELCOME -> {
                 WelcomeScreen(
                     isDarkTheme = isDarkTheme,
+                    hasExistingAccount = hasExistingAccount,
+                    onBack = { currentScreen = AuthScreen.UNLOCK },
                     onCreateSeed = { currentScreen = AuthScreen.SEED_PHRASE },
                     onImportSeed = { currentScreen = AuthScreen.IMPORT_SEED }
                 )

app/src/main/java/com/rosetta/messenger/ui/auth/WelcomeScreen.kt

@@ -35,6 +35,8 @@ val AuthSurfaceLight = Color(0xFFF5F5F5)
 @Composable
 fun WelcomeScreen(
     isDarkTheme: Boolean,
+    hasExistingAccount: Boolean = false,
+    onBack: () -> Unit = {},
     onCreateSeed: () -> Unit,
     onImportSeed: () -> Unit
 ) {
@@ -67,6 +69,22 @@ fun WelcomeScreen(
             .fillMaxSize()
             .background(backgroundColor)
     ) {
+        // Back button when coming from UnlockScreen
+        if (hasExistingAccount) {
+            IconButton(
+                onClick = onBack,
+                modifier = Modifier
+                    .statusBarsPadding()
+                    .padding(4.dp)
+            ) {
+                Icon(
+                    Icons.Default.ArrowBack,
+                    contentDescription = "Back",
+                    tint = textColor
+                )
+            }
+        }
+        
         Column(
             modifier = Modifier
                 .fillMaxSize()

app/src/main/java/com/rosetta/messenger/ui/chats/ChatsListScreen.kt

@@ -436,8 +436,12 @@ fun ChatsListScreen(
                         .clip(RoundedCornerShape(12.dp))
                         .background(Color(0x20FF3B30))
                         .clickable {
-                            scope.launch { drawerState.close() }
+                            scope.launch { 
-                            onLogout()
+                                drawerState.close()
+                                // Wait for drawer to close before logout
+                                kotlinx.coroutines.delay(150)
+                                onLogout()
+                            }
                         }
                         .padding(horizontal = 16.dp, vertical = 12.dp),
                     verticalAlignment = Alignment.CenterVertically
@@ -484,6 +488,7 @@ fun ChatsListScreen(
                         animationSpec = tween(400)
                     )
                 ) {
+                    key(isDarkTheme) {
                     TopAppBar(
                         navigationIcon = {
                             IconButton(
@@ -704,6 +709,7 @@ fun ChatsListScreen(
                             actionIconContentColor = textColor
                         )
                     )
+                    }
                 }
             },
             floatingActionButton = {