fix: 为 openviking-server 添加 --version 并修复 AGFS 模式判断

[qin-ctx]

Description

为 openviking-server 命令添加 --version 参数支持，并修复 AGFS 初始化时多余的条件判断。

Related Issue

close #354

Type of Change

• Bug fix (non-breaking change that fixes an issue)

Changes Made

• openviking/server/bootstrap.py：添加 --version 参数，通过 argparse 的 action="version" 实现，版本号从 openviking.__version__ 读取
• openviking/service/core.py：移除 AGFS 初始化中 config.agfs.backend == "local" 的多余条件，使 http-client 模式下始终启动 AGFSManager

Testing

• openviking-server --version 正常输出版本号（openviking-server 0.2.1.dev23）
• openviking-server --help 正常显示 --version 选项
• ov --version（Rust CLI）确认已支持（openviking 0.2.0）
• pre-commit hooks（ruff check + ruff format）通过

Checklist

• My code follows the project's coding style
• I have performed a self-review of my code
• My changes generate no new warnings

Additional Notes

openviking-server 之前缺少 --version 参数，agent 误调用 openviking-server --version 时会报 option not found 导致安装流程中断。

🤖 Generated with Claude Code

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}