feat: Safely set last logged account public key using null safety

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

@@ -82,8 +82,12 @@ fun UnlockScreen(
     var searchQuery by remember { mutableStateOf("") }
     val searchFocusRequester = remember { FocusRequester() }
     
-    // Load accounts
+    // Load accounts and pre-select last used account
     LaunchedEffect(Unit) {
+        // ⚡ СИНХРОННОЕ чтение последнего аккаунта ДО загрузки списка
+        val lastLoggedKey = accountManager.getLastLoggedPublicKey()
+        Log.d("UnlockScreen", "🔍 Last logged account from SharedPrefs: ${lastLoggedKey?.take(16) ?: "none"}")
+        
         val allAccounts = accountManager.getAllAccounts()
         accounts = allAccounts.map { acc ->
             AccountItem(
@@ -93,30 +97,26 @@ fun UnlockScreen(
             )
         }
         
-        // Get last logged account from SharedPreferences (synchronous, reliable)
-        val lastLoggedKey = accountManager.getLastLoggedPublicKey()
+        Log.d("UnlockScreen", "📋 Available accounts: ${accounts.map { "${it.name}:${it.publicKey.take(8)}" }}")
         
-        Log.d("UnlockScreen", "Loading accounts. lastLoggedKey=$lastLoggedKey")
-        Log.d("UnlockScreen", "Available accounts: ${accounts.map { "${it.name}:${it.publicKey.take(8)}" }}")
-        
-        // Find the target account - prioritize selectedAccountId, then lastLoggedKey
+        // Find the target account - приоритет: selectedAccountId > lastLoggedKey > первый
         val targetAccount = when {
-            selectedAccountId != null -> {
-                Log.d("UnlockScreen", "Using selectedAccountId: $selectedAccountId")
+            !selectedAccountId.isNullOrEmpty() -> {
+                Log.d("UnlockScreen", "✅ Using selectedAccountId: ${selectedAccountId.take(16)}")
                 accounts.find { it.publicKey == selectedAccountId }
             }
-            lastLoggedKey != null -> {
-                Log.d("UnlockScreen", "Using lastLoggedKey: ${lastLoggedKey.take(8)}")
+            !lastLoggedKey.isNullOrEmpty() -> {
+                Log.d("UnlockScreen", "✅ Using lastLoggedKey: ${lastLoggedKey.take(16)}")
                 accounts.find { it.publicKey == lastLoggedKey }
             }
             else -> {
-                Log.d("UnlockScreen", "No lastLoggedKey, using first account")
-                null
+                Log.d("UnlockScreen", "⚠️ No preference, using first account")
+                accounts.firstOrNull()
             }
         }
         
         selectedAccount = targetAccount ?: accounts.firstOrNull()
-        Log.d("UnlockScreen", "Final selected: ${selectedAccount?.name}:${selectedAccount?.publicKey?.take(8)}")
+        Log.d("UnlockScreen", "🎯 Final selected: ${selectedAccount?.name} (${selectedAccount?.publicKey?.take(16)})")
     }
     
     // Filter accounts by search