ui: Real account button (avatar + display name), stable list keys

The top bar now mirrors SmartTube: a 44dp circle with the actual user
avatar (persisted at login alongside the display name; falls back to
the person icon) and the display name next to it.

Scrolling jank: add stable keys to grids and rows (item/channel ids)
- without keys Compose rebinds the whole list during scroll and
re-fires every AsyncImage + focus request, which is the realistic
culprit for the 2fps vertical scrolling on the TV.

app/src/main/java/net/jeena/jtubetv/data/PeerTubeRepository.kt

@@ -86,7 +86,14 @@ class PeerTubeRepository(
                     .addConverterFactory(json.asConverterFactory("application/json; charset=utf-8".toMediaType()))
                     .build()
                     .create(PeerTubeApi::class.java)
-                store.accountName = meApi.me().username
+                val me = meApi.me()
+                store.accountName = me.username
+                store.userDisplayName = me.displayName ?: me.username
+                me.avatars.maxByOrNull { it.width }?.let { avatar ->
+                    store.userAvatarUrl = avatar.fileUrl
+                        ?.takeIf { url -> url.startsWith("http") }
+                        ?: apiUrlOf(base) + avatar.path
+                }
             } catch (_: Exception) {
                 store.accountName = username.substringBefore('@') // best effort fallback
             }

app/src/main/java/net/jeena/jtubetv/data/api/Dtos.kt

@@ -137,5 +137,6 @@ data class VideoTokenFiles(
 @Serializable
 data class UserDto(
     val username: String,
+    val displayName: String? = null,
     val avatars: List<Avatar> = emptyList(),
 )

app/src/main/java/net/jeena/jtubetv/data/auth/TokenStore.kt

@@ -48,6 +48,15 @@ class TokenStore(context: Context) {
         get() = prefs.getString("refreshToken", null)
         private set(value) = prefs.edit().putString("refreshToken", value).apply()
 
+    /** Display name + avatar for the account button (from users/me at login). */
+    var userDisplayName: String?
+        get() = prefs.getString("userDisplayName", null)
+        set(value) = prefs.edit().putString("userDisplayName", value).apply()
+
+    var userAvatarUrl: String?
+        get() = prefs.getString("userAvatarUrl", null)
+        set(value) = prefs.edit().putString("userAvatarUrl", value).apply()
+
     /** Real account name from users/me — may differ from the login input (email). */
     var accountName: String?
         get() = prefs.getString("accountName", null)

app/src/main/java/net/jeena/jtubetv/ui/screens/ChannelsScreen.kt

@@ -262,7 +262,7 @@ private fun ChannelCardRow(
         contentPadding = PaddingValues(horizontal = 12.dp),
         horizontalArrangement = Arrangement.spacedBy(4.dp),
     ) {
-        itemsIndexed(channels) { index, channel ->
+        itemsIndexed(channels, key = { _, c -> c.name + "@" + c.host }) { index, channel ->
             val fr = remember { FocusRequester() }
             focusRequesters[index] = fr
             ChannelCard(

app/src/main/java/net/jeena/jtubetv/ui/screens/HomeRows.kt

@@ -299,7 +299,7 @@ fun FocusScrollRow(
         contentPadding = PaddingValues(horizontal = 12.dp),
         horizontalArrangement = Arrangement.spacedBy(4.dp),
     ) {
-        itemsIndexed(videos) { index, video ->
+        itemsIndexed(videos, key = { _, video -> "v" + video.id }) { index, video ->
             val fr = remember { FocusRequester() }
             focusRequesters[index] = fr
             VideoCard(

app/src/main/java/net/jeena/jtubetv/ui/screens/HomeScreen.kt

@@ -239,31 +239,53 @@ private fun TopBar(
             desc = "Search",
             onClick = onSearchClick,
         )
-        // "Who is logged in" — account button with the username (SmartTube shows the user).
+        // "Who is logged in" — account button: avatar circle + display name (SmartTube).
         val accountFocused = remember { mutableStateOf(false) }
         Row(
             modifier = Modifier
-                .clip(CircleShape)
                 .onFocusChanged { accountFocused.value = it.isFocused }
-                .background(if (accountFocused.value) Color(0x33FFFFFF) else Color.Transparent)
+                .background(Color.Transparent)
                 .then(
                     if (accountFocused.value) Modifier.border(3.dp, Color.White, CircleShape)
                     else Modifier
                 )
                 .focusable()
-                .clickable(onClick = onAccountClick)
-                .padding(6.dp),
+                .clickable(onClick = onAccountClick),
             verticalAlignment = Alignment.CenterVertically,
             horizontalArrangement = androidx.compose.foundation.layout.Arrangement.spacedBy(8.dp),
         ) {
-            Icon(
-                imageVector = Icons.Filled.AccountCircle,
-                contentDescription = "Menu",
-                tint = Color(0xFFCCCCCC),
-            )
+            val avatarUrl = AppGraph.tokenStore.userAvatarUrl
+            if (avatarUrl != null) {
+                coil.compose.AsyncImage(
+                    model = coil.request.ImageRequest.Builder(androidx.compose.ui.platform.LocalContext.current)
+                        .data(avatarUrl)
+                        .size(96)
+                        .build(),
+                    contentDescription = "Account",
+                    modifier = Modifier
+                        .size(44.dp)
+                        .clip(CircleShape)
+                        .background(Color(0xFF262626)),
+                )
+            } else {
+                Box(
+                    modifier = Modifier
+                        .size(44.dp)
+                        .clip(CircleShape)
+                        .background(Color(0xFF262626)),
+                    contentAlignment = Alignment.Center,
+                ) {
+                    Icon(
+                        imageVector = Icons.Filled.AccountCircle,
+                        contentDescription = "Account",
+                        tint = Color(0xFFCCCCCC),
+                    )
+                }
+            }
             Text(
-                text = AppGraph.tokenStore.username?.substringBefore('@') ?: "Account",
-                color = Color(0xFFCCCCCC),
+                text = AppGraph.tokenStore.userDisplayName
+                    ?: AppGraph.tokenStore.username?.substringBefore('@') ?: "Account",
+                color = Color(0xFFB0B0B0),
                 style = androidx.compose.material3.MaterialTheme.typography.bodyMedium,
                 modifier = Modifier.padding(end = 8.dp),
             )

app/src/main/java/net/jeena/jtubetv/ui/screens/list/VideoListScreen.kt

@@ -124,7 +124,7 @@ fun VideoListScreen(
         state = gridState,
         modifier = Modifier.fillMaxSize().padding(vertical = 8.dp),
     ) {
-        itemsIndexed(items) { index, item ->
+        itemsIndexed(items, key = { _, item -> itemStableKey(item) }) { index, item ->
             val video: VideoDto = when (item) {
                 is VideoListItem.HistoryEntry -> item.history.video
                 is VideoListItem.Video -> item.video
@@ -189,6 +189,12 @@ private fun SearchHeader(viewModel: VideoListViewModel) {
     }
 }
 
+private fun itemStableKey(item: VideoListItem): String =
+    when (item) {
+        is VideoListItem.Video -> "v" + item.video.id
+        is VideoListItem.HistoryEntry -> "h" + item.history.video.id
+    }
+
 private fun sourceKey(source: ListSource): String = when (source) {
     is ListSource.Channel -> "channel:${source.handle}"
     else -> source::class.java.simpleName