refactor(ao): background loops only orchestrate; cleanup/reconcile endpoints enqueue

- separate qB sync timer from the planning timer
- threshold cleanup, reserved-plan and pending-import sweeps, 6h reconcile enqueue
  engine tasks with time-slot idempotency keys instead of running inline
- pending-import sweep selects by completed_at (sync refreshes updated_at every round)
- POST /download-cache/cleanup and /library/reconcile return {taskId, runId} (202);
  web jumps to the engine run page
- test: a 50MB verifyAndImport in progress does not delay qB sync

Co-Authored-By: Claude Opus 5.5 <[email protected]>

apps/web/app/components/downloads/cache-volumes.tsx

@@ -1,5 +1,6 @@
 import type { Dashboard } from "@umt/contracts";
 import { Brush, HardDrive } from "lucide-react";
+import { useNavigate } from "react-router";
 import { toast } from "sonner";
 import { useCacheCleanup, useCacheVolumes } from "~/api/downloads.ts";
 import { ConfirmDialog } from "~/components/console/confirm-dialog.tsx";
@@ -79,6 +80,7 @@ function VolumeBar({ v }: { v: Volume }) {
 export function CacheVolumes() {
   const vols = useCacheVolumes();
   const cleanup = useCacheCleanup();
+  const navigate = useNavigate();
   return (
     <section className="pg-slab mb-6 rounded-xl p-4">
       <div className="mb-3 flex flex-wrap items-center justify-between gap-2">
@@ -96,10 +98,8 @@ export function CacheVolumes() {
           onConfirm={() =>
             cleanup.mutateAsync(undefined).then(
               (r) => {
-                const vols = (r.report as { volumes?: { removed?: unknown[]; skipped?: unknown[] }[] }).volumes ?? [];
-                const removed = vols.reduce((n, v) => n + (v.removed?.length ?? 0), 0);
-                const skipped = vols.reduce((n, v) => n + (v.skipped?.length ?? 0), 0);
-                toast.success(`清理完成:移除 ${removed} 个任务的缓存${skipped ? `,${skipped} 个因保留/H&R 跳过` : ""}`);
+                toast.success(`已排队清理任务 ${r.taskId.slice(0, 8)}`, { description: "后台执行,结果见任务详情" });
+                navigate(`/console/engine/${r.runId}`);
               },
               (e) => toast.error(errorMessage(e)),
             )