[FEATURE] /color setting should persist when resuming a session with --resume

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

Description

When setting a session color via /color blue (or any color), the setting is lost when the session is resumed via
claude --resume <session-id>. The session starts with the default color each time.

## Steps to reproduce

1. Start a new session: claude
2. Set a color: /color blue
3. Exit the session
4. Resume: claude --resume <session-id>
5. Color is reset to default

## Expected behavior

The /color setting should be stored as session metadata and restored automatically when resuming.

## Additional context

There are existing issues for /rename not persisting on resume (#23610, #25090, #25509, #26240), but /color
persistence is not covered by any of them. Ideally both /color and /rename would be persisted together as part of
session metadata.

Proposed Solution

Proposed solution

Store /color (and /rename) in the session's metadata object inside sessions-index.json
alongside the existing session ID and timestamp fields. For example:

{
"id": "0c075f5b-1d71-48aa-8e47-b45e59bae229",
"name": "TFS discussion",
"color": "blue",
...
}

On --resume, read these fields from the index and apply them before rendering the session.
This is the same place /rename should persist (#23610), so both could be fixed together
with a single metadata read on resume.

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_