Fix settings English translations / 修复设置页英文翻译

[AntonyLeons]

English

Summary

• Replaced hardcoded Chinese UI strings in the Settings modal and settings sections with existing useLocale() translation lookups.
• Added matching English and Simplified Chinese translation keys for General, LLM, Proxy, MCP Server, MITM Proxy, update status, log tools, certificate actions, and related settings toasts.
• Kept the existing i18n structure intact without adding new dependencies or translation machinery.

Why

When switching the app language to English, several Settings labels, buttons, tooltips, and toast messages still appeared in Chinese. This makes the English UI inconsistent, especially in the settings area.

Verification

• Confirmed SettingsModal.tsx and src/renderer/components/settings/* no longer contain hardcoded Chinese UI strings.
• Confirmed all new translation keys exist in both en.ts and zh.ts.

中文

变更概要

• 将设置弹窗和各个设置分区中硬编码的中文 UI 文案替换为现有的 useLocale() 翻译调用。
• 为通用设置、LLM、代理、MCP Server、MITM 代理、更新状态、日志工具、证书操作以及相关 toast 提示补充了英文和简体中文翻译 key。
• 保持现有 i18n 结构不变，没有引入新的依赖或额外翻译机制。

修改原因

切换到英文后，设置页中仍有部分标签、按钮、提示气泡和 toast 文案显示中文，导致英文界面不一致，尤其是在 Settings 区域比较明显。

验证

• 已确认 SettingsModal.tsx 和 src/renderer/components/settings/* 中不再包含硬编码中文 UI 字符串。
• 已确认新增翻译 key 在 en.ts 和 zh.ts 中均存在。