fix: Stop button stays after a server restart cuts off a reply (#32205)

When the server restarted while a reply was streaming, the page reconnected but kept showing the cut-off reply as still generating. The Stop button stayed and the next message got no answer until the page was reloaded. After reconnecting, the page now checks whether the reply is still being generated and, if not, shows it as finished, which is how it behaved before the shared chats change.

Fixes #32204

src/lib/components/chat/Chat.svelte

@@ -2865,6 +2865,7 @@
 								!messageHasPendingAskUser(message)
 							) {
 								message.done = true;
+								history = history;
 							}
 						}
 					}