新增 iframe 结果接口与圆桌 Step3 结果绘制

- 公开 API：GET /api/public/embed/sessions/{sessionId}/result 返回 messages、generated_text、generated_files
- 圆桌 Step3：内置 roundtable-report 智能体、report/init 与结果绘制 UI

Co-authored-by: Cursor <cursoragent@cursor.com>

frontend-web/src/core/embed/status-api.ts

@@ -10,6 +10,12 @@ export type EmbedSessionStatus = {
   latest_run_status: string | null;
 };
 
+export type EmbedSessionResult = EmbedSessionStatus & {
+  messages: Record<string, unknown>[];
+  generated_text: string;
+  generated_files: string[];
+};
+
 async function parseEmbedError(response: Response): Promise<string> {
   const body = await response.json().catch(() => ({}));
   if (typeof body.detail === "string") {
@@ -50,3 +56,18 @@ export async function getEmbedSessionStatus(
   }
   return response.json() as Promise<EmbedSessionStatus>;
 }
+
+/** Fetch full messages, generated text, and artifact paths — parent uses sessionId only. */
+export async function getEmbedSessionResult(
+  sessionId: string,
+): Promise<EmbedSessionResult> {
+  const base = getBackendBaseURL();
+  const response = await fetch(
+    `${base}/api/public/embed/sessions/${encodeURIComponent(sessionId)}/result`,
+    { credentials: "omit" },
+  );
+  if (!response.ok) {
+    throw new Error(await parseEmbedError(response));
+  }
+  return response.json() as Promise<EmbedSessionResult>;
+}