feat(downloads): fold download plans into download panel (DL-3)

- Waiting plans (approval / disk space / automation off / queued) are
  active-segment rows on /download-tasks/board, merged by created_at,
  counted, with approve / cancel actions; ?plan= deep links and legacy
  /downloads/plans routes redirect to the panel
- Download detail shows "why this download" (source, purpose, replaced
  version, reasons); raw evaluation in tech info
- Failed / cancelled / expired plans appear in the entity download
  history; rejected / revoked / expired approvals close draft plans
- New GET /acquisition-plans/{id}/why, POST /acquisition-plans/{id}/cancel
- User-facing copy no longer says 下载计划; glossary updated

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

apps/web/app/routes/console/audit.tsx

@@ -38,7 +38,8 @@ const ACTION_LABEL: Record<string, string> = {
   "pi_upstream.oauth_logout": "退出订阅登录",
   "schedule.run_now": "立即执行定时任务",
   "schedule.skip": "跳过定时任务",
-  "acquisition_plan.manual_submit": "手动提交下载计划",
+  "acquisition_plan.manual_submit": "手动提交下载",
+  "acquisition_plan.cancel": "取消下载",
   "engine.run_retry": "重跑任务",
   "capability.invoke": "智能体操作",
   "capability.denied": "智能体操作被拒绝",
@@ -75,7 +76,7 @@ const TARGET_LABEL: Record<string, string> = {
   site_account: "站点账号",
   feed_source: "RSS",
   engine_run: "任务",
-  acquisition_plan: "下载计划",
+  acquisition_plan: "下载",
   download_task: "下载任务",
   media_entity: "作品",
   source_release: "资源",