feat: implement fullscreen image viewer in SearchScreen and refactor MediaTabContent

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

@@ -185,8 +185,18 @@ fun SearchScreen(
     // Focus requester для автофокуса
     val focusRequester = remember { FocusRequester() }
 
+    // Fullscreen image viewer state — lifted to top level for true fullscreen overlay
+    var showImageViewer by remember { mutableStateOf(false) }
+    var imageViewerInitialIndex by remember { mutableStateOf(0) }
+    var imageViewerImages by remember { mutableStateOf<List<com.rosetta.messenger.ui.chats.components.ViewableImage>>(emptyList()) }
+    var imageViewerPrivateKey by remember { mutableStateOf("") }
+
     // 🔥 Обработка системного жеста Back
     BackHandler {
+        if (showImageViewer) {
+            showImageViewer = false
+            return@BackHandler
+        }
         hideKeyboardInstantly()
         searchViewModel.clearSearchQuery()
         onBackClick()
@@ -212,6 +222,7 @@ fun SearchScreen(
         }
     }
 
+    Box(modifier = Modifier.fillMaxSize()) {
     Scaffold(
             topBar = {
                 // Хедер как в Telegram: стрелка назад + поле ввода
@@ -366,7 +377,13 @@ fun SearchScreen(
                             currentUserPublicKey = currentUserPublicKey,
                             isDarkTheme = isDarkTheme,
                             textColor = textColor,
-                            secondaryTextColor = secondaryTextColor
+                            secondaryTextColor = secondaryTextColor,
+                            onOpenImageViewer = { images, index, privateKey ->
+                                imageViewerImages = images
+                                imageViewerInitialIndex = index
+                                imageViewerPrivateKey = privateKey
+                                showImageViewer = true
+                            }
                     )
                 }
                 SearchTab.DOWNLOADS -> {
@@ -386,7 +403,22 @@ fun SearchScreen(
                 }
             }
         }
+    } // End Scaffold
+
+    // Fullscreen image viewer overlay — rendered OUTSIDE Scaffold for true fullscreen
+    if (showImageViewer && imageViewerImages.isNotEmpty()) {
+        com.rosetta.messenger.ui.chats.components.ImageViewerScreen(
+                images = imageViewerImages,
+                initialIndex = imageViewerInitialIndex.coerceIn(0, imageViewerImages.lastIndex),
+                privateKey = imageViewerPrivateKey,
+                onDismiss = {
+                    showImageViewer = false
+                    imageViewerImages = emptyList()
+                },
+                isDarkTheme = isDarkTheme
+        )
     }
+    } // End outer Box
 }
 
 // ═══════════════════════════════════════════════════════════
@@ -800,7 +832,8 @@ private fun MediaTabContent(
         currentUserPublicKey: String,
         isDarkTheme: Boolean,
         textColor: Color,
-        secondaryTextColor: Color
+        secondaryTextColor: Color,
+        onOpenImageViewer: (images: List<com.rosetta.messenger.ui.chats.components.ViewableImage>, initialIndex: Int, privateKey: String) -> Unit = { _, _, _ -> }
 ) {
     val context = LocalContext.current
     var mediaItems by remember { mutableStateOf<List<MediaItem>>(emptyList()) }
@@ -810,10 +843,6 @@ private fun MediaTabContent(
         com.rosetta.messenger.data.MessageRepository.getInstance(context).getCurrentPrivateKey().orEmpty()
     }
 
-    // Fullscreen image viewer state
-    var showImageViewer by remember { mutableStateOf(false) }
-    var imageViewerInitialIndex by remember { mutableStateOf(0) }
-
     val viewerImages = remember(mediaItems) {
         mediaItems.map { item ->
             com.rosetta.messenger.ui.chats.components.ViewableImage(
@@ -903,24 +932,14 @@ private fun MediaTabContent(
                             currentUserPublicKey = currentUserPublicKey,
                             privateKey = privateKey,
                             onClick = {
-                                imageViewerInitialIndex = if (index >= 0) index else 0
+                                val idx = if (index >= 0) index else 0
-                                showImageViewer = true
+                                onOpenImageViewer(viewerImages, idx, privateKey)
                             }
                     )
                 }
             }
         }
 
-        // Fullscreen image viewer overlay
-        if (showImageViewer && viewerImages.isNotEmpty()) {
-            com.rosetta.messenger.ui.chats.components.ImageViewerScreen(
-                    images = viewerImages,
-                    initialIndex = imageViewerInitialIndex.coerceIn(0, viewerImages.lastIndex),
-                    privateKey = privateKey,
-                    onDismiss = { showImageViewer = false },
-                    isDarkTheme = isDarkTheme
-            )
-        }
     }
 }