feat(skills): add search and batch actions for installed skills

[JrDw0]

Summary / 概述

This PR improves the installed skills management experience in the Skills panel.

Changes included:

• Add search for installed skills by name, description, repository, and directory
• Add batch mode for installed skills
• Support selecting filtered skills only
• Support batch enable/disable for a chosen target app
• Support batch delete for selected skills
• Add i18n entries for en / ja / zh
• Add tests for search, filtered selection, and batch target app behavior

这个 PR 改进了 Skills 面板中“已安装技能”的管理体验。

包含的改动：

• 支持按名称、描述、仓库和目录搜索已安装技能
• 为已安装技能新增批量管理模式
• 支持仅选择当前筛选结果中的技能
• 支持按指定目标应用批量启用/禁用技能
• 支持批量删除所选技能
• 补充 en / ja / zh 国际化文案
• 增加搜索、筛选选择、目标应用批量操作相关测试

Screenshots / 截图

After / 修改后

Checklist / 检查清单

• pnpm typecheck passes / 通过 TypeScript 类型检查
• pnpm format:check passes / 通过代码格式检查
• cargo clippy passes (if Rust code changed) / 未修改 Rust 代码，不适用
• Updated i18n files if user-facing text changed / 已更新国际化文件

[farion1231]

@codex review

[chatgpt-codex-connector]

Codex Review: Didn't find any major issues. Delightful!

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[JrDw0]

@farion1231 似乎本地分支的测试用例有点老，现在已经更新了，麻烦再跑一下，另外想问下有开发者组织吗，想加入帮忙维护贡献cc-switch

[crmmc]

期待合并，这个功能实现看起来不错！