Restore quick delete action in the sessions view

Describe the feature or problem you'd like to solve

The sessions list used to support deleting a session directly from the list (a quick delete/keyboard action on the highlighted row). That option is gone, and there is now no good way to delete sessions.

Proposed solution

• Re-add a delete action in the sessions view that operates on the highlighted session without opening it (e.g.  d  or  Del  key, with a confirmation prompt).
• Support deleting multiple sessions in one pass (multi-select, or stay in the list after each delete).
• Deleting from the list should not create a new session; the user should remain in the sessions view with the deleted entry removed.

Example prompts or workflows

No response

Additional context

The only remaining path is  /session delete , which has two significant problems:

1. It requires opening a session first. You must resume/enter a session before you can delete it, so cleaning up several stale sessions means repeatedly opening sessions you have no interest in.
2. It spawns a replacement session. After deleting, the CLI immediately creates a brand-new session. So deleting N sessions leaves you with N new empty sessions to clean up, which is extremely frustrating.

まず、セッションビューと既存の /session delete コマンドを追跡し、特にハイライトされた行、キーボード操作、確認、セッション作成がどのように処理されているかを確認します。最初に現在の削除フローを検証してください。完了の条件は、リストからハイライトされたセッションを1つ以上削除し、それらを開いたり代替セッションを作成したりせず、ユーザーがセッションビューに留まることです。