Refactor/account store provider

[runyunzhou]

Description

本 PR 将现有账号、用户、用户组和 API Key 持久化逻辑重构为可插拔的异步 AccountStore 架构。

现有 AGFS 文件存储实现被抽离为 FileStore，APIKeyManager 收敛为与具体存储实现无关的协调层。认证、OAuth、管理接口、删除流程和历史数据迁移等调用链同步迁移到新的异步契约，同时保持现有文件路径、认证行为和默认配置兼容。

本 PR 仅包含 Account Store 基础抽象和 File provider，不包含 MySQL、Redis 或 Redis + MySQL provider 实现。

Human Involvement

• A human participated in the implementation or review loop
• This PR was generated entirely by AI agents without human participation in the loop

Related Issue

N/A

Type of Change

• Bug fix (non-breaking change that fixes an issue)
• New feature (non-breaking change that adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation update
• Refactoring (no functional changes)
• Performance improvement
• Test update

Changes Made

• 新增异步 AccountStore 契约及共享数据模型，统一账号、用户、用户组、凭证、删除状态和认证相关存储操作。
• 将原有 AGFS 账号与 API Key 存储逻辑抽离为 FileStore，保留既有文件路径、加密、Argon2 哈希、删除 fence 和凭证轮换语义。
• 将 APIKeyManager 收敛为 provider 无关的异步协调层，并新增集中式 Store 装配入口。
• 将 API Key、Trusted、OAuth、MCP、Admin、资源访问、账号删除和历史迁移等调用链迁移到异步接口。
• 保留多实例文件存储 watcher，并通过显式 fresh management read 保证关键管理操作读取最新状态。
• 补充 FileStore 原子写入、凭证唯一性、删除并发保护、fresh 查询、装配和身份认证等回归测试。
• 更新中英文配置及认证文档，说明 Account Store 配置和兼容行为。

Testing

• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• I have tested this on the following platforms:
  • Linux
  • macOS
  • Windows

验证结果：

• pytest tests/server/test_account_services.py tests/server/test_store_assembly.py
  • 13 passed
• git diff --check main...refactor/account-store-provider
  • Passed
• 已对 main...refactor/account-store-provider 的完整差异执行代码审查，未发现 P0/P1 级别问题。

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• Any dependent changes have been merged and published

Screenshots (if applicable)

N/A

Additional Notes

[qin-ctx]

AccountStore 抽象能收敛现有存储职责，重构方向合理。当前需要先解决 Studio 将不可读的哈希密钥标为可绑定的问题；另有两处注册路径的额外存储读取，详见 inline comments。

[qin-ctx]

当前 Head 存在已复现的自定义认证插件启动回归，修复前暂不建议合入，详见行级评论。