[Feature request] Create a sample Figma file as a community reference

### Description

New users of the Annotation Toolkit would benefit from seeing real examples of how annotations are applied to actual design mockups. A sample Figma file that demonstrates the toolkit in use would serve as a practical learning resource.

### Requested change

Create a companion Figma community file that shows annotated mockups, demonstrating how to use various annotation types in context.
Open questions

- Should the sample file use GitHub UI as the subject, or something more generic that any team could relate to?
- Should it aim to cover all annotation component types, or focus on the most common ones? If a subset, which ones would be most helpful to showcase first?

### Why

Seeing annotations applied in context is one of the most effective ways to learn how to use them. A reference file would lower the barrier to entry for new users and give teams a starting point they can reference when annotating their own work.

先解決有關 mockup 主題以及要涵蓋哪些註解元件類型的未解問題。建立並發布一個配套的 Figma community 檔案，其中包含帶註解的 mockup，用於展示 toolkit 在實際情境中的使用；當它為新使用者提供可用的參考時，這項工作就完成了。

由索引模型根據 Issue 內容生成。