feat: add GitHub skill installation support

- Implemented functionality to install skills from GitHub URLs.
- Updated API to handle new installation requests from GitHub.
- Enhanced UI to allow users to input GitHub skill URLs for installation.
- Added translations for new GitHub installation features in English, Thai, and Chinese.
- Created tests for the new skill installation service and API routes to ensure proper functionality.

src/i18n/locales/zh/skills.json

@@ -90,6 +90,11 @@
     "installDialogSubtitle": "默认展示 Explore，也可以输入关键词搜索。",
     "sourceLabel": "来源",
     "sourceClawHub": "ClawHub",
+    "githubInstallLabel": "从 GitHub 安装",
+    "githubUrlPlaceholder": "粘贴 GitHub /blob/.../SKILL.md 或 /tree/... 技能链接",
+    "githubInstallAction": "安装链接",
+    "githubInstallHint": "支持 public github.com 的技能目录，并安装到 \"{{path}}\"。",
+    "githubUrlRequired": "请先输入 GitHub 技能链接。",
     "securityNote": "安装前请点击技能卡片，在 ClawHub 上查看其文档和安全信息。",
     "manualInstallHint": "遇到网络问题？您可以随时从 ClawHub.ai 下载技能压缩包，并将其解压至 \"{{path}}\" 目录来完成手动安装。",
     "searching": "正在搜索 ClawHub...",