Setting to limit number of workflow runs displayed in the sidebar

**Is your feature request related to a problem? Please describe.**
The current list of workflow runs in the sidebar can be very long and cluttered. I often only care about the most recent runs (e.g., the last 3) to check their status quickly.

**Describe the solution you'd like**
I would like a configuration setting (e.g., `github-actions.workflows.limit`) that allows me to define the number of latest runs shown per workflow in the sidebar. For example, setting it to `3` would only show the 3 most recent runs.

**Describe alternatives you've considered**
Currently, I have to scroll through a long list of history which is distracting.

**Additional context**
This would help keep the UI clean and focused on immediate feedback.

該 issue 沒有指出檔案、測試或進入點。先定位 workflow-run 側邊欄的渲染和擴充功能設定宣告，然後追蹤執行記錄的取得與顯示方式。當類似 github-actions.workflows.limit 的設定將每個工作流程限制為設定數量的最新執行記錄時，即視為完成。

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