[BUG] Rust panic on Korean UTF-8 string boundary in status line

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

Body:
## Environment

• Claude Code version: 2.0.76
• OS: WSL2 (Linux 6.6.87.2-microsoft-standard-WSL2)

Claude Code crashes when processing Korean text. The error indicates incorrect UTF-8 byte slicing on multi-byte Korean characters.

What Should Happen?

shutdown Claude code

Error Messages/Logs

thread '' panicked at /rustc/.../library/core/src/str/mod.rs:833:21:
  byte index 8 is not a char boundary; it is inside '트' (bytes 6..9) of 데이트    
  note: run with RUST_BACKTRACE=1 environment variable to display a backtrace      
  fatal runtime error: failed to initiate panic, error 5, aborting
  Aborted (core dumped)

Steps to Reproduce

Using Claude Code with Korean language input (exact trigger unknown).

Claude Model

None

Is this a regression?

Yes, this worked in a previous version

Last Working Version

_No response_

Claude Code Version

2.0.76

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_