CLAUDE_CODE_NO_FLICKER=1 breaks Korean (CJK) text paste on Windows

Description

When CLAUDE_CODE_NO_FLICKER=1 is set, copying Korean (CJK) text from the Claude Code terminal output and pasting it elsewhere results in garbled/corrupted characters on Windows.

Steps to Reproduce

1. Set environment variable CLAUDE_CODE_NO_FLICKER=1
2. Launch Claude Code on Windows
3. Have Claude Code output Korean text in the terminal
4. Select and copy the Korean text from the terminal
5. Paste it into another application (e.g., text editor, browser)
6. Observe that the pasted Korean characters are broken/garbled

Expected Behavior

Korean (CJK) text copied from the terminal should be pasted correctly in other applications, as it does without the CLAUDE_CODE_NO_FLICKER=1 option.

Actual Behavior

Copied Korean characters appear garbled/corrupted when pasted elsewhere.

Environment

• OS: Windows 11 Pro (10.0.26200)
• Shell: bash
• WSL: Not affected — the issue does not occur in WSL, only in native Windows terminal.

Additional Context

This appears to be a Windows-specific issue with the no-flicker rendering mode not handling multi-byte characters correctly during terminal output/copy operations.