feat: Add delivery confirmation for incoming messages in ProtocolManager

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

@@ -5,6 +5,7 @@ import androidx.activity.ComponentActivity
 import androidx.activity.compose.setContent
 import androidx.activity.enableEdgeToEdge
 import androidx.compose.animation.*
+import androidx.compose.animation.core.FastOutSlowInEasing
 import androidx.compose.animation.core.tween
 import androidx.compose.foundation.background
 import androidx.compose.foundation.layout.Box
@@ -220,29 +221,38 @@ fun MainScreen(
     // Навигация между экранами
     var selectedUser by remember { mutableStateOf<SearchUser?>(null) }
     
-    // Анимированный переход между чатами
+    // Анимированный переход между чатами - плавный crossfade без прыжков
     AnimatedContent(
         targetState = selectedUser,
         transitionSpec = {
-            if (targetState != null) {
-                // Открытие чата - слайд слева
-                slideInHorizontally(
-                    initialOffsetX = { it },
-                    animationSpec = tween(300)
-                ) togetherWith slideOutHorizontally(
-                    targetOffsetX = { -it / 3 },
-                    animationSpec = tween(300)
+            // Плавный crossfade для избежания "прыжков" header'а
+            val enterAnim = fadeIn(
+                animationSpec = tween(
+                    durationMillis = 250,
+                    easing = FastOutSlowInEasing
                 )
-            } else {
-                // Закрытие чата - слайд справа
-                slideInHorizontally(
-                    initialOffsetX = { -it / 3 },
-                    animationSpec = tween(300)
-                ) togetherWith slideOutHorizontally(
-                    targetOffsetX = { it },
-                    animationSpec = tween(300)
+            ) + slideInHorizontally(
+                initialOffsetX = { if (targetState != null) it / 4 else -it / 4 },
+                animationSpec = tween(
+                    durationMillis = 300,
+                    easing = FastOutSlowInEasing
                 )
-            }
+            )
+            
+            val exitAnim = fadeOut(
+                animationSpec = tween(
+                    durationMillis = 200,
+                    easing = FastOutSlowInEasing
+                )
+            ) + slideOutHorizontally(
+                targetOffsetX = { if (targetState != null) -it / 6 else it / 6 },
+                animationSpec = tween(
+                    durationMillis = 300,
+                    easing = FastOutSlowInEasing
+                )
+            )
+            
+            enterAnim togetherWith exitAnim using SizeTransform(clip = false)
         },
         label = "chatNavigation"
     ) { user ->