[FEATURE] Add command to delete chat sessions

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

Currently, there is no built-in command to delete specific chat sessions in Claude Code. While claude --resume allows users to view and resume previous sessions, there's no way to remove unwanted or outdated sessions through the CLI.

Proposed Solution

Add a command to delete specific chat sessions, such as:
```bash
claude --delete-session <session-id>

Or alternatively:
claude session delete <session-id>

Alternative Solutions

_No response_

Priority

Medium - Would be very helpful

Feature Category

CLI commands and flags

Use Case Example

_No response_

Additional Context

_No response_