[FEATURE]: Support session deletion via cli

[xywang18]

Feature hasn't been suggested before.

• I have verified this feature I'm about to request hasn't been suggested before.

Describe the enhancement you want to request

The session sub-command currently only supports listing all sessions and does not support deleting a specific session. It makes script inconvenient.

[github-actions]

This might be related to #8677, which requests a /delete command for deleting the current session in the TUI. While your feature request focuses on CLI support for the session subcommand, both aim to improve session deletion functionality. You may want to check if one of these approaches would better meet your needs or if they could be combined.