perf(ui): load recent tasks with bounded summaries (#16851)

Replace passive recent-task detail reads with bounded, authorized summaries. Keep account isolation, stored history, task actions, and live recovery behavior.

Overlap access checks with shell settings and avoid duplicate session and health reads on the first healthy socket opening. Retain domain reconciliation.

Add focused coverage and local performance evidence. Isolate the existing cache capacity test from entry expiry on slow CI runners.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

ui/src/components/ShellConfigurationGate.tsx

@@ -0,0 +1,7 @@
+import { Outlet } from "@/lib/router";
+import { PaperclipLoading } from "./AnimatedPaperclipIcon";
+
+/** Keep shell selection stable while the independent access gate loads. */
+export function ShellConfigurationGate({ loaded }: { loaded: boolean }) {
+  return loaded ? <Outlet /> : <PaperclipLoading />;
+}