fix typo in a dialog for ai summary

Author: williamstein

src/packages/frontend/chat/llm-msg-summarize.tsx

@@ -69,7 +69,7 @@ export function SummarizeThread({
             a {short ? "short" : "detailed"} summary of the conversation.
           </Paragraph>
           <Paragraph>
-            Summary lenght:{" "}
+            Summary length:{" "}
             <Switch
               checked={!short}
               onChange={(v) => setShort(!v)}