Channel context menu: hide Delete for the default channel (it can be renamed but not deleted; server already enforces this)

app/shared/src/commonMain/kotlin/iris/ui/screens/ChatScreen.kt

@@ -1082,7 +1082,8 @@ private fun IconImage(base64: String, size: Dp) {
 
 /**
  * Long-press / right-click context menu for a channel row: rename, favorite
- * (state-aware), icon (state-aware), delete.
+ * (state-aware), icon (state-aware), delete. The default channel cannot be
+ * deleted (the server enforces this too), so its "Delete" item is hidden.
  */
 @Composable
 private fun ChannelContextMenu(
@@ -1105,7 +1106,9 @@ private fun ChannelContextMenu(
             text = { Text(if (hasIcon) "Change icon" else "Add icon") },
             onClick = { onDismiss(); onEditIcon() },
         )
-        DropdownMenuItem(text = { Text("Delete") }, onClick = { onDismiss(); onDelete() })
+        if (!ch.isDefault) {
+            DropdownMenuItem(text = { Text("Delete") }, onClick = { onDismiss(); onDelete() })
+        }
     }
 }