Feature request: expose /rename as a programmatically invokable tool

Problem

/rename is a built-in CLI command that can only be typed interactively by the user. There is no way for skills, agents, or hooks to rename the current session programmatically.

Use case

Our team has a /dev-starter skill that resolves a task ID (e.g., CHRONOS-1222) and needs to rename the session to [C-1222] short description for easy identification. Currently the skill has to ask the user to manually type /rename, which breaks the automation flow.

Proposed solution

Expose /rename as either:

• A tool callable from skills/agents (like other built-in commands)
• A CLI flag that works mid-session (e.g., claude session rename "name")
• A writable session metadata property

Current workaround

Skill reminds the user to run /rename manually at the end of its flow.