feat(webui): add temporary chat mode

webui/src/lib/temporary-chat.ts

@@ -0,0 +1,21 @@
+import type { ChatSummary } from "./types";
+
+export const TEMPORARY_CHAT_ID_PREFIX = "temporary-";
+export const TEMPORARY_CHAT_ROUTE_KEY = "__temporary_chat__";
+
+export function isTemporaryChatId(value: string): boolean {
+  return value.startsWith(TEMPORARY_CHAT_ID_PREFIX);
+}
+
+export function createTemporaryChatSession(): ChatSummary {
+  const chatId = `${TEMPORARY_CHAT_ID_PREFIX}${crypto.randomUUID()}`;
+  const now = new Date().toISOString();
+  return {
+    key: `websocket:${chatId}`,
+    channel: "websocket",
+    chatId,
+    createdAt: now,
+    updatedAt: now,
+    preview: "",
+  };
+}