feat: add scroll indicator

frontend/src/app/workspace/chats/[thread_id]/page.tsx

@@ -135,7 +135,7 @@ export default function ChatPage() {
                 "absolute top-0 right-0 left-0 z-30 flex h-12 shrink-0 items-center px-4",
                 isNewThread
                   ? "bg-background/0 backdrop-blur-none"
-                  : "bg-background/80 backdrop-blur",
+                  : "bg-background/80 shadow-xs backdrop-blur",
               )}
             >
               <div className="flex w-full items-center text-sm font-medium">
@@ -163,7 +163,7 @@ export default function ChatPage() {
             <main className="flex min-h-0 grow flex-col">
               <div className="flex size-full justify-center">
                 <MessageList
-                  className="size-full"
+                  className={cn("size-full", !isNewThread && "pt-10")}
                   threadId={threadId}
                   thread={thread}
                   paddingBottom={todoListCollapsed ? 160 : 280}

frontend/src/components/ai-elements/conversation.tsx

@@ -50,7 +50,7 @@ export const ConversationEmptyState = ({
   <div
     className={cn(
       "flex size-full flex-col items-center justify-center gap-3 p-8 text-center",
-      className
+      className,
     )}
     {...props}
   >
@@ -58,7 +58,7 @@ export const ConversationEmptyState = ({
       <>
         {icon && <div className="text-muted-foreground">{icon}</div>}
         <div className="space-y-1">
-          <h3 className="font-medium text-sm">{title}</h3>
+          <h3 className="text-sm font-medium">{title}</h3>
           {description && (
             <p className="text-muted-foreground text-sm">{description}</p>
           )}
@@ -85,7 +85,7 @@ export const ConversationScrollButton = ({
       <Button
         className={cn(
           "absolute bottom-4 left-[50%] translate-x-[-50%] rounded-full",
-          className
+          className,
         )}
         onClick={handleScrollToBottom}
         size="icon"