Remote Control: timestamp system-reminder wraps to multiple lines in terminal

Summary

When using Remote Control (mobile Claude app → CLI session), every incoming message is prefixed with a <system-reminder>Message sent at ... UTC.</system-reminder> block. In the terminal this renders across two lines, consuming extra vertical space.

Steps to reproduce

1. Start a Claude Code CLI session.
2. Connect via /remote-control.
3. Send any message from the Claude mobile app.
4. Observe the terminal prompt area.

Observed behavior

❯ <system-reminder>Message sent at Sun 2026-06-14 13:45:23
  UTC.</system-reminder>
  Hello from mobile

The timestamp block wraps mid-content, so the user message starts on line 3 instead of line 1.

Expected behavior

Either:

• The timestamp renders as a single line (no wrap), or
• It is hidden from the terminal display entirely (it is already visible to the model as a system-reminder tag — it does not need to be echoed in the prompt area)