fix(plugins): remove filesystem recommendation

[musnows]

中文

变更

• 从插件市场推荐列表移除 Filesystem MCP server。
• 删除对应的中英文 locale 残留文案。
• 增加回归测试，确保 Filesystem 不再作为推荐项出现。

原因

Kun 已经内置 read/write/edit/bash 等本地工具，推荐额外的 filesystem MCP server 会造成重复能力，缺少实际收益。

验证

• npm test -- src/renderer/src/components/PluginMarketplaceView.test.ts
• npm run typecheck

English

Changes

• Removed the Filesystem MCP server from the plugin marketplace recommendations.
• Removed the unused English and Chinese locale strings.
• Added a regression test to keep Filesystem out of the recommended list.

Why

Kun already ships built-in read/write/edit/bash local tools, so recommending the filesystem MCP server duplicates existing capability without clear benefit.

Validation

• npm test -- src/renderer/src/components/PluginMarketplaceView.test.ts
• npm run typecheck