[Translation] Add full Traditional Chinese (zh-TW) translation

[wunsiangcheng]

提案：新增完整繁體中文翻譯（Traditional Chinese / zh-TW）

Hi, I'd like to contribute a full Traditional Chinese (zh-TW) translation of all lesson docs in this repository.

What I'm proposing

• Translate all docs/en.md files to docs/zh-TW.md (or zh.md — open to guidance on naming)
• Follow the existing lesson structure exactly
• Translate content only, not code
• Work phase by phase, starting from Phase 0

Before I start, a few questions

1. File naming: Should I use zh-TW.md (to distinguish from Simplified Chinese) or zh.md?
2. Is anyone else working on this? I'd like to avoid duplicate effort.
3. PR preference: One PR per phase, or one per lesson?
4. Any style guide for Chinese technical terms (e.g. 模型 vs 模式, 嵌入 vs 向量表示)?

Happy to coordinate however works best for the project. Let me know if there's anything I should be aware of before starting.

Thanks!