feat: skills add private repository support/skills管理中添加私有仓库支持

[Mecurryy]

## English ### What does this PR do? - Enables the skills management system to connect to private repositories (e.g., GitLab, GitHub) by introducing token-based authentication. - Modifies the `SkillRepo` data structure to persist private repository credentials and metadata.

Changes include

• New feature (non-breaking change)
• Database schema update (if applicable)

How to test

1. Navigate to the Skills Management page.
2. Add a new private repository URL (e.g., https://gitlab.com/user/private-skill).
3. Enter a valid authentication token and save.
4. Verify the system can access the repository and list the skills correctly.

中文

这个 PR 做了什么？

• 通过引入基于令牌的认证，使技能管理系统能够连接到私有仓库（如 GitLab、GitHub）。
• 修改了 SkillRepo 数据结构，以持久化私有仓库的凭证和元数据。

改动包含

• 新功能（非破坏性变更）
• 数据库 schema 更新（如适用）

如何测试

1. 进入技能管理页面。
2. 添加一个新的私有仓库 URL（例如 https://gitlab.com/user/private-skill）。
3. 输入有效的认证令牌并保存。
4. 验证系统能够访问该仓库并正确列出技能。

[xzxiaoshan]

单 gitlab 还是有局限性，我直接性解决了所有仓库源的问题： #1410

[farion1231]

Hi, I owe you an apology for the long silence. As the sole maintainer of this project, I've been overwhelmed and fell behind on reviews — but that's on me, not on you. Your contribution matters and I will review this PR. If it needs a rebase, just let me know or I can handle it. Thank you for your time and patience.