v0.11.0 - Plugin tree comparison

Compare the whole plugin around a Skill

diff-tree compares two selected directory trees, including plugin metadata and hooks outside a nested SKILL.md.

node src/cli.js diff-tree ./examples/plugin-source ./examples/plugin-installed

This fictional example returns 1 for differences. In one isolated macOS test with skills@1.7.4, a nested Skill was copied while the selected enclosing plugin files were absent from the installed Skill directory. Compare the actual source and installation directories for your setup: moved files also appear as differences. The command does not establish plugin loading or execute hooks.

中文版：diff-tree 可只读对比两个目录中的插件文件，示例展示 Skill 外层配置未出现在所选安装目录的情况；目录位置变化也会显示差异，结果不代表插件已被加载。