[FEATURE]: Add delete shortcut in Esc+Esc session picker

Feature Request

Description:
When pressing Esc+Esc to open the session picker in Claude Code CLI, there is currently no way to delete a session directly from the picker UI.

Current behavior:
The session picker supports navigation (↑/↓), preview (P), and rename (R), but there is no delete option.

Requested behavior:
Add a keyboard shortcut (e.g., D or Delete) in the session picker to delete/remove a selected session, with a confirmation prompt to prevent accidental deletion.

Use case:
Users accumulate many sessions over time and want to clean up old or irrelevant sessions directly from the interactive picker without having to manually find and delete files from the filesystem (~/.claude/projects/).

Workaround:
Currently users must manually delete session JSON files from the local filesystem.