Trigger Workflow preselects stale/unrelated branch instead of active workspace branch

從開啟工作流程觸發對話框的擴充功能命令或 UI 開始，追蹤其預設分支/ref 的解析方式。使用作用中的 workspace 分支和連結的 worktree 進行重現，然後確認該對話框是否優先使用作用中 workspace 儲存庫的 HEAD，且只有在無法判定該 HEAD 時才回退。

Extension

GitHub Actions for VS Code

Summary

When triggering a workflow from VS Code, the branch/ref dropdown preselects an unrelated branch (often from a linked worktree or prior context) instead of the branch currently checked out in the active workspace folder.

Expected behavior

Default selected branch/ref should be the branch currently checked out in the active workspace repository.

Actual behavior

The dialog defaults to a different branch than the active workspace branch.

Repro (generic)

1. Create a repository with multiple branches.
2. Create at least one additional Git linked worktree with a different branch checked out.
3. In VS Code, open the original workspace folder on branch feature/current.
4. Use the extension command/UI to trigger a workflow manually.
5. Observe the preselected branch/ref in the trigger dialog.

Observed result

The preselected branch/ref is not feature/current; it appears to come from stale/cached/worktree context.

Notes

• Manually switching the branch in the dialog works, but the default is misleading and easy to miss.
• This can cause accidental workflow runs on the wrong branch.

Suggested fix

Prefer branch/ref resolution from the active workspace repository HEAD (and only fall back to cached/worktree-derived refs if workspace HEAD cannot be determined).