docs(aliyundrive): explain callback concurrency

[nostalume]

Description / 描述

Document the new Aliyun Drive Open Callback Concurrency setting in English and Chinese, including:

• proxy-only applicability and the default value of 1;
• conservative sharing by Aliyun user identity and minimum-value resolution across mounts;
• the one-second admission wait and three-attempt provider-capacity retry bound;
• standard S3 SlowDown / HTTP 503 behavior after capacity is exhausted.

新增阿里云盘 Open“回调并发数”的中英文说明，包括代理模式适用范围、默认值 1、同一用户挂载共享最小配置、一秒准入等待、三次容量重试，以及容量耗尽后的 S3 SlowDown / HTTP 503 行为。

Motivation and Context / 背景

Operators need the configuration and retry behavior documented alongside the implementation for Aliyun callback concurrency failures.

Relates to OpenListTeam/OpenList#2969

Checklist / 检查清单

• I have read the CONTRIBUTING document.
  我已阅读 CONTRIBUTING 文档。
• I have formatted my code or documentation with prettier or other appropriate formatter.
  我已使用 prettier 或其他适当的格式化工具格式化提交的代码或文档。
• I have updated all supported languages (including Chinese and English) for documentation. (If it's needed)
  我已为所有支持语言（包括中文和英文）更新文档内容。 (若适用)
• I have verified that the written documentation or code is properly formatted, with no syntax errors, spelling mistakes.
  我已确认编写的文档或代码格式正确, 无语法错误, 拼写错误。
• I have updated the repository accordingly (If it's needed).
  我已相应更新了相关仓库（若适用）。
  • OpenList #3071
  • OpenList-Frontend Not required; the field is metadata-driven.

Testing / 测试

• pnpm exec prettier --check pages/guide/drivers/aliyundrive_open.md
• pnpm exec valaxy build --ssg

The SSG build completed successfully. It emitted existing warnings for external version-source timeouts, an icon set, and the Badge component.

AI Disclosure / AI 使用声明

Codex assisted with documentation drafting, Chinese/English translation, formatting, and review. Commit attribution is included. This draft remains pending the author's human review before it is marked ready.