fix(ui): P0-4 — SaaS settings page crash from paginated API response

listRelayTasks() expected RelayTaskInfo[] but API returns
{items:[], total:0, page:1, page_size:20}. When setTasks() received
the paginated object, tasks.map() crashed during render, triggering
the ErrorBoundary fallback "SaaS 平台加载失败".

Fix: extract .items from paginated response with Array.isArray fallback.
Also adds onError logging to ErrorBoundary wrappers for easier debugging.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

desktop/src/lib/saas-relay.ts

@@ -16,14 +16,15 @@ export function installRelayMethods(ClientClass: { prototype: any }): void {
 
   // --- Relay Task Management ---
 
-  /** List relay tasks for the current user */
+  /** List relay tasks for the current user (extracts items from paginated response) */
   proto.listRelayTasks = async function (this: { request<T>(method: string, path: string, body?: unknown): Promise<T> }, query?: { status?: string; page?: number; page_size?: number }): Promise<RelayTaskInfo[]> {
     const params = new URLSearchParams();
     if (query?.status) params.set('status', query.status);
     if (query?.page) params.set('page', String(query.page));
     if (query?.page_size) params.set('page_size', String(query.page_size));
     const qs = params.toString();
-    return this.request<RelayTaskInfo[]>('GET', `/api/v1/relay/tasks${qs ? '?' + qs : ''}`);
+    const result = await this.request<{ items: RelayTaskInfo[]; total: number }>('GET', `/api/v1/relay/tasks${qs ? '?' + qs : ''}`);
+    return Array.isArray(result) ? result : (result?.items ?? []);
   };
 
   /** Retry a failed relay task (admin only) */