[BUG] "Background this session?" dialog promises artifact comment auto-replies on Pro/Max, where artifacts can't receive comments

### Preflight Checklist

- [x] I have searched existing issues and this hasn't been reported yet
- [x] This is a single bug report
- [x] I am using the latest version of Claude Code

### What's Wrong?

After publishing an artifact on a **Pro** plan, pressing ← to background the session shows this confirmation:

> Background this session? Automatic replies to Artifact comments continue in the background session. You'll see a summary of the replies when you return.

On Pro, an artifact can never receive comments, so this dialog promises work that can't happen. Per the [artifacts docs](https://code.claude.com/docs/en/artifacts#collect-comments-on-an-artifact):

- Comments need "a Team or Enterprise plan, because only an artifact you share within your organization takes comments."
- "On Pro and Max plans, a public link is the only way to share an artifact."
- "If you share an artifact publicly, viewers can't comment on it."

On Pro and Max, then, no artifact can ever take a comment, yet the backgrounding dialog still mentions automatic comment replies and asks for confirmation because of them.

Note: the live subscription armed after a publish may still be useful on these plans. It also reports republishes of the artifact from elsewhere. This report is only about the comment auto-reply promise and the confirmation it triggers.

### What Should Happen?

The backgrounding dialog should mention comment auto-replies only when the artifact can actually receive comments. On plans where it can't, such as Pro and Max, background the session without the prompt, or mention only what will keep running, such as republish notifications.

### Steps to Reproduce

1. Sign in with `/login` on a Pro account.
2. Ask Claude to publish any artifact.
3. After the publish completes, press ← to background the session.
4. The "Background this session? Automatic replies to Artifact comments continue…" dialog appears.

### Claude Model

Opus

### Is this a regression?

I don't know

### Claude Code Version

2.1.270 (Claude Code)

### Platform

Anthropic API

### Operating System

macOS (Darwin 25.6.0)

### Terminal/Shell

Terminal.app (macOS), zsh