state-specific icons

- add html snapshots for all the states of an issue and PR (draft/open/different kinds of closed, etc)
- parse them into the spot
- render them in the table
- **hard part** - items will change state after they were sent/closed. how do we handle that?
- if we adopt #98
- we could set icon on a per-URL basis, so when the icon transitions for a given issue or PR url, we change all the icons for that URL

未指定檔案、測試或進入點。首先追蹤 issue 和 pull request 狀態在表格中如何被解析及呈現，然後檢視 #98 所提出的按 URL 處理方式如何應對後續的狀態變更。完成的標準是 HTML 快照涵蓋列出的狀態、這些狀態產生預期的圖示，且狀態轉換會更新相同 URL 的所有圖示。

由索引模型根據 Issue 內容生成。