Show Android preview loading states and retry failed neighbors

tools/chatgui-android/app/src/main/java/com/utun/chat/ui/screens/AvatarViewerScreen.kt

@@ -39,6 +39,7 @@ fun AvatarViewerScreen(group: String?, owner: Long, name: String, onClose: () ->
     var original by remember { mutableStateOf<Bitmap?>(null) }
     var failed by remember { mutableStateOf(false) }
     var catalogFailed by remember { mutableStateOf(false) }
+    var failedPreviews by remember { mutableStateOf(emptySet<String>()) }
     var retry by remember { mutableStateOf(0) }
     LaunchedEffect(account,revision) { if (account==0L) onClose() }
     LaunchedEffect(source?.first,source?.second?.avatarServer,source?.second?.avatarFile,retry) {
@@ -74,10 +75,11 @@ fun AvatarViewerScreen(group: String?, owner: Long, name: String, onClose: () ->
     LaunchedEffect(source?.first,source?.second?.avatarServer,visible,retry) {
         val (channel,member)=source ?: return@LaunchedEffect
         previews=previews.filterKeys { it in visible }
+        failedPreviews=emptySet()
         coroutineScope { visible.filter { it!=selected && it !in previews }.forEach { file -> launch {
             try { previews=previews+(file to repository.loadAvatar(channel,member.copy(avatarFile=file),false)) }
             catch (e: CancellationException) { throw e }
-            catch (e: Exception) { LogManager.addLog("WARN","Avatar","Neighbor failed file=$file: ${e.message}") }
+            catch (e: Exception) { failedPreviews=failedPreviews+file; LogManager.addLog("WARN","Avatar","Neighbor failed file=$file: ${e.message}") }
         } } }
     }
     fun move(delta: Int) { val next=index+delta; if (next in files.indices) selected=files[next] }
@@ -93,7 +95,7 @@ fun AvatarViewerScreen(group: String?, owner: Long, name: String, onClose: () ->
                 else if (source!=null && !failed) CircularProgressIndicator()
                 else Text(stringResource(if (source==null) R.string.avatar_none else R.string.avatar_load_failed),color=Color.White)
             }
-            if (failed || catalogFailed) TextButton(onClick={ retry++ },modifier=Modifier.align(Alignment.CenterHorizontally)) {
+            if (failed || catalogFailed || failedPreviews.isNotEmpty()) TextButton(onClick={ retry++ },modifier=Modifier.align(Alignment.CenterHorizontally)) {
                 Text(stringResource(R.string.avatar_retry))
             } else if (original==null && source!=null) LinearProgressIndicator(Modifier.fillMaxWidth())
             if (index>=0) Text("${index+1} / ${files.size}",color=Color.White,modifier=Modifier.align(Alignment.CenterHorizontally))
@@ -107,6 +109,10 @@ fun AvatarViewerScreen(group: String?, owner: Long, name: String, onClose: () ->
                         .clickable(enabled=file!=null) { if (file!=null) selected=file },contentAlignment=Alignment.Center) {
                         previews[file]?.let { Image(it.asImageBitmap(),contentDescription=null,contentScale=ContentScale.Crop,
                             modifier=Modifier.fillMaxSize()) }
+                        if (file!=null && file !in previews) {
+                            if (file in failedPreviews) Text("!",color=Color.White)
+                            else CircularProgressIndicator(Modifier.size(18.dp),strokeWidth=2.dp)
+                        }
                     }
                 }
                 TextButton(enabled=index>=0 && index+1<files.size,onClick={ move(1) },contentPadding=PaddingValues(4.dp),