Remove lastSeenAt from handle update in chat API

The lastSeenAt field is no longer set when updating the handle in the chat receive API route. This may be due to a change in how user activity is tracked or to simplify the update payload.

src/app/api/chat/receive/route.ts

@@ -102,8 +102,7 @@ export async function POST(request: NextRequest) {
             target: handleRegistry.handle,
             set: {
                 did: senderDid,
-                nodeDomain: senderNodeDomain,
+                nodeDomain: senderNodeDomain
-                lastSeenAt: new Date()
             }
         });