feat(tasks): add copy queue controls and task visibility

[fryeggs]

Summary / 摘要

This PR improves the task page for large copy queues and adds an administrator-only pause/resume control for queued copy work. Running and waiting counts are visible, running tasks can be isolated, unfinished tasks refresh frequently, completed tasks refresh and sort by completion time, and non-English locales fall back to English for newly added keys.

本 PR 面向大型复制队列改进任务页面，并为管理员增加排队复制任务的暂停/恢复控制。页面显示运行中/等待中数量，可只查看运行任务；未完成任务高频刷新，已完成任务按完成时间刷新和排序；非英语语言缺少新键时自动回退到英语。

• This PR has breaking changes.
• This PR changes public API, config, storage format, or migration behavior.
• This PR requires corresponding changes in related repositories. The backend persistence companion PR is linked below.

Related repository PRs / 关联仓库 PR:

• OpenList: feat(task): persist task timestamps across restarts OpenList#2914
• OpenList-Docs: not required.

Testing / 测试

• pnpm exec prettier --check src/app/i18n.ts src/lang/en/tasks.json src/pages/manage/tasks/Copy.tsx src/pages/manage/tasks/Task.tsx src/pages/manage/tasks/Tasks.tsx
• pnpm build
• The built production asset contains the copy queue control and was checked in the deployed OpenList runtime.
• Manual browser test in this clean upstream worktree: not run because the live deployment was intentionally kept paused at zero workers during validation.

Checklist / 检查清单

• I have read CONTRIBUTING.
• I confirm this contribution follows the repository license, contribution policy, and code of conduct.
• I have formatted the changed code with prettier.
• I have requested review from relevant maintainers or code owners where applicable.

AI Disclosure / AI 使用声明

• This PR includes AI-assisted content.

Tools used / 使用工具:

• Codex

Usage scope / 使用范围:

• Code generation / 代码生成

• Refactoring / 重构

• Tests / 测试

• Translation / 翻译 fallback keys

• Review assistance / 审查辅助

• I have reviewed and validated all AI-assisted content included in this PR.

• I have ensured that this AI-assisted commit includes Co-Authored-By attribution.

• I can reproduce the checked behavior from the committed source and test commands without relying on hidden runtime state.