Desktop app: allow "Start locally" as the default action on task chips

In the Claude Code desktop app (Code tab), task suggestion chips created by a session (`spawn_task`) show two actions: "Start with worktree" as the primary button and "Start locally" as secondary.

My workflow is main-branch only, no worktrees, so I click "Start locally" every time. There is no setting to change the default. I tested `worktree.bgIsolation: "none"` in settings.json (with an app restart) and the chip still defaults to worktree.

Request: a setting (settings.json or app preference) to pick the default chip action, or have the chip respect `worktree.bgIsolation`.

Version: desktop app on macOS, Claude Code 2.1.239.

Start with the Code tab flow for task suggestion chips created by session spawn_task calls, and compare its default selection with the worktree.bgIsolation setting in settings.json. Done means users can choose "Start locally" as the default, or the chip derives that choice from worktree.bgIsolation, while both actions remain available.

Do mô hình lập chỉ mục viết ra từ nội dung của issue.