🚫 AI Policy / AI 政策

• We explicitly reject AI-generated PRs that have not been manually verified.
• 本项目拒绝接受任何未经人工复核的 AI 生成的 PR。
• Low-quality AI PRs will be closed immediately. / 低质量的 AI PR 会被直接关闭。
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Description / 描述

This PR adds a Notion-compatible formula copy format to Voyager.

Changes included:

• add a new Notion option in popup settings for formula copy format
• support copying formulas in a Notion-friendly wrapped format
• keep existing LaTeX, UnicodeMath, and no-dollar options intact
• update related i18n labels
• add regression coverage for formula copy behavior

User impact:

• users can choose a dedicated copy format when pasting formulas into Notion
• existing formula copy behavior remains available for other workflows

本次PR为Voyager新增了兼容Notion的公式复制格式。

包含的变更：

• 在弹窗设置中新增“Notion”选项作为公式复制格式
• 支持以Notion的格式复制公式
• 保留原有的“LaTeX”、“UnicodeMath”及“无美元符号”选项不变
• 更新相关 i18n 标签
• 为公式复制行为添加测试

用户影响：

• 用户向Notion粘贴公式时，可选择专用复制格式
• 现有公式复制功能仍适用于其他工作流程

Related Issue / 相关 Issue

#515

Visual Proof / 可视化证据

Browser Testing / 浏览器测试

• [✅] Chrome / Edge (Chromium): Tested / 已测试
• [✅] Firefox: Tested (Mandatory) / 已测试（必填）
• Safari: Tested (Optional) or labeled as unsupported / 已测试（可选）或已标注为不支持

Checklist / 检查清单

• [✅] I have manually verified that the feature works as intended. / 我已手动验证功能按预期工作。
• [✅] I have confirmed that this PR does not break existing functionality. / 我已确认此 PR 不会破坏原有功能。
• [✅] I have run bun run lint, bun run typecheck, bun run format and bun run build. / 我已运行代码校验、类型检查、格式化及构建。
• [✅] I have added/updated necessary tests and they pass (bun run test). / 我已添加/更新了必要的测试并确保通过（bun run test）。