feat: Enhance screen transition animations and preserve state during navigation for improved user experience

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

@@ -6,6 +6,8 @@ import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
 import androidx.compose.animation.*
 import androidx.compose.animation.core.FastOutSlowInEasing
+import androidx.compose.animation.core.Spring
+import androidx.compose.animation.core.spring
 import androidx.compose.animation.core.tween
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Box
@@ -19,6 +21,7 @@ import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.unit.IntOffset
 import androidx.compose.ui.unit.dp
 import androidx.compose.ui.unit.sp
 import com.rosetta.messenger.data.AccountManager
@@ -231,12 +234,82 @@ fun MainScreen(
     var selectedUser by remember { mutableStateOf<SearchUser?>(null) }
     var showSearchScreen by remember { mutableStateOf(false) }
     
-    // Анимированный переход между экранами
+    // Анимированный переход между экранами - Telegram-style
     AnimatedContent(
         targetState = Triple(selectedUser, showSearchScreen, Unit),
         transitionSpec = {
-            // Только плавный fade без смещения - чтобы header не прыгал
-            fadeIn(
+            val isEnteringChat = targetState.first != null && initialState.first == null
+            val isExitingChat = targetState.first == null && initialState.first != null
+            val isEnteringSearch = targetState.second && !initialState.second
+            val isExitingSearch = !targetState.second && initialState.second
+            
+            when {
+                // 🚀 Вход в чат - slide справа + fade (как Telegram)
+                isEnteringChat -> {
+                    slideInHorizontally(
+                        initialOffsetX = { fullWidth -> fullWidth / 3 },  // Начинаем на 1/3 экрана справа
+                        animationSpec = tween(
+                            durationMillis = 250,
+                            easing = FastOutSlowInEasing
+                        )
+                    ) + fadeIn(
+                        initialAlpha = 0.3f,
+                        animationSpec = tween(
+                            durationMillis = 200,
+                            easing = FastOutSlowInEasing
+                        )
+                    ) togetherWith slideOutHorizontally(
+                        targetOffsetX = { fullWidth -> -fullWidth / 6 },  // Список уходит немного влево
+                        animationSpec = tween(
+                            durationMillis = 250,
+                            easing = FastOutSlowInEasing
+                        )
+                    ) + fadeOut(
+                        targetAlpha = 0.5f,
+                        animationSpec = tween(
+                            durationMillis = 200,
+                            easing = FastOutSlowInEasing
+                        )
+                    )
+                }
+                
+                // 🔙 Выход из чата - slide вправо + fade (быстрее)
+                isExitingChat -> {
+                    slideInHorizontally(
+                        initialOffsetX = { fullWidth -> -fullWidth / 6 },  // Список возвращается слева
+                        animationSpec = tween(
+                            durationMillis = 200,
+                            easing = FastOutSlowInEasing
+                        )
+                    ) + fadeIn(
+                        initialAlpha = 0.5f,
+                        animationSpec = tween(
+                            durationMillis = 180,
+                            easing = FastOutSlowInEasing
+                        )
+                    ) togetherWith slideOutHorizontally(
+                        targetOffsetX = { fullWidth -> fullWidth / 2 },  // Чат уходит вправо
+                        animationSpec = tween(
+                            durationMillis = 200,
+                            easing = FastOutSlowInEasing
+                        )
+                    ) + fadeOut(
+                        animationSpec = tween(
+                            durationMillis = 180,
+                            easing = FastOutSlowInEasing
+                        )
+                    )
+                }
+                
+                // 🔍 Вход в поиск - slide снизу
+                isEnteringSearch -> {
+                    slideInVertically(
+                        initialOffsetY = { fullHeight -> fullHeight / 4 },
+                        animationSpec = tween(
+                            durationMillis = 220,
+                            easing = FastOutSlowInEasing
+                        )
+                    ) + fadeIn(
                         animationSpec = tween(
                             durationMillis = 200,
                             easing = FastOutSlowInEasing
@@ -246,7 +319,39 @@ fun MainScreen(
                             durationMillis = 150,
                             easing = FastOutSlowInEasing
                         )
-            ) using SizeTransform(clip = false)
+                    )
+                }
+                
+                // ❌ Выход из поиска - slide вниз
+                isExitingSearch -> {
+                    fadeIn(
+                        animationSpec = tween(
+                            durationMillis = 180,
+                            easing = FastOutSlowInEasing
+                        )
+                    ) togetherWith slideOutVertically(
+                        targetOffsetY = { fullHeight -> fullHeight / 4 },
+                        animationSpec = tween(
+                            durationMillis = 200,
+                            easing = FastOutSlowInEasing
+                        )
+                    ) + fadeOut(
+                        animationSpec = tween(
+                            durationMillis = 150,
+                            easing = FastOutSlowInEasing
+                        )
+                    )
+                }
+                
+                // Default fade
+                else -> {
+                    fadeIn(
+                        animationSpec = tween(durationMillis = 200)
+                    ) togetherWith fadeOut(
+                        animationSpec = tween(durationMillis = 150)
+                    )
+                }
+            }
         },
         label = "screenNavigation"
     ) { (user, isSearchOpen, _) ->

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

@@ -14,6 +14,7 @@ import androidx.compose.material.icons.outlined.*
 import androidx.compose.material3.*
 import androidx.compose.runtime.*
 import androidx.compose.runtime.Immutable
+import androidx.compose.runtime.saveable.rememberSaveable
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.clip
@@ -194,9 +195,9 @@ fun ChatsListScreen(
     // Status dialog state
     var showStatusDialog by remember { mutableStateOf(false) }
 
-    var visible by remember { mutableStateOf(false) }
-
-    LaunchedEffect(Unit) { visible = true }
+    // 🔥 Используем rememberSaveable чтобы сохранить состояние при навигации
+    // Header сразу visible = true, без анимации при возврате из чата
+    var visible by rememberSaveable { mutableStateOf(true) }
 
     // Dev console dialog - commented out for now
     /*