v1.20.1

Patch Changes

• ed0c4b0: Fix install failing on Git repositories whose default branch is not main.

  Previously, when a skill reference had no version spec (e.g. @scope/my-skill or gitlab-host:owner/repo/subpath), reskill hard-coded the clone ref to main. This broke installs on any repo whose real default branch was something else (most commonly master on self-hosted GitLab EE instances).

  Now the resolver introduces a new 'default' version type. When no version spec is provided, reskill auto-detects the repository's actual default branch via git ls-remote --symref <repoUrl> HEAD (the same mechanism already used by @latest when no tags exist). Explicit @branch:main / @main (exact tag) references continue to work unchanged.

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  修复默认分支不是 main 的 Git 仓库无法 install 的问题。

  此前未指定版本（如 @scope/my-skill 或 gitlab-host:owner/repo/subpath）时，reskill 会把 clone 分支硬编码为 main，导致默认分支为其他名字的仓库（最常见的是自托管 GitLab EE 上的 master 仓库）无法安装。

  现在解析器新增 'default' 版本类型：未指定版本时通过 git ls-remote --symref <repoUrl> HEAD 自动探测仓库真实的默认分支（与 @latest 无 tag 时的回退机制一致）。显式指定 @branch:main / @main（精确 tag）的行为保持不变。