Improve scroll handling and robustness for chat UI

Added 'overscroll-behavior: contain' to body and Chromebook scroll containers to prevent unwanted scroll chaining. Updated scrollToBottom utilities to handle null/undefined containers and errors gracefully. Fixed ChatDetail to use the correct scroll handler function.

components/dashboard/ChatTable.tsx

@@ -354,7 +354,7 @@ export default function ChatTable() {
                           <div>
                             <div className="font-semibold text-sm flex items-center gap-2">
                               {chat.telegramUsername ? (
-                                <span className="text-blue-400">@{chat.telegramUsername}</span>
+                                <span>@{chat.telegramUsername}</span>
                               ) : (
                                 <span className="text-foreground">Customer {chat.buyerId.slice(0, 6)}...</span>
                               )}