fix: build errors (useEffect cleanup, null→undefined)

src/components/ChatPanel.tsx

@@ -38,7 +38,7 @@ export default function ChatPanel({ projectId }: Props) {
         setMessages((prev) => [...prev, data as Message]);
       }
     });
-    return unsub;
+    return () => { unsub?.(); };
   }, [chatId]);
 
   useEffect(() => {

src/components/CreateProjectModal.tsx

@@ -30,7 +30,7 @@ export default function CreateProjectModal({ onCreated, onClose }: Props) {
       const project = await createProject({
         name: name.trim(),
         slug,
-        description: description.trim() || null,
+        description: description.trim() || undefined,
       });
       onCreated(project);
     } catch (err) {