Change repo-assist to delegate to task-specific workflows with fewer permissions

Currently repo-assist is one generic workflow which combines multiple permissions

We want to change this to be a workflow that delegates to specific task workflows which may have reduced, different safe outputs and permissions

先定位目前的 repo-assist 工作流程，並檢視它如何結合權限與輸出。定義工作專屬的工作流程與委派界線；完成的意思是每項工作只使用其所需的權限，並產生預期的安全輸出。

由索引模型根據 Issue 內容生成。