fix: click the prompt button to hide hints when it's already shown

app/components/chat.tsx

@@ -789,6 +789,12 @@ export function Chat() {
           scrollToBottom={scrollToBottom}
           hitBottom={hitBottom}
           showPromptHints={() => {
+            // Click again to close
+            if (promptHints.length > 0) {
+              setPromptHints([]);
+              return;
+            }
+
             inputRef.current?.focus();
             onSearch("");
           }}