Thai combining characters cause display glitch and incorrect backspace behavior on Windows

Describe the bug
When typing Thai text in Claude Code's input on Windows, combining characters (vowels like ่ ้ ็ ั) overlap visually with the preceding consonant, and pressing backspace deletes both the vowel and the consonant instead of just the vowel.

To reproduce

1. Open Claude Code on Windows
2. Type any Thai word with a tone mark or above/below vowel (e.g. ก่อน, แก้)
3. Press backspace once

Expected behavior
Backspace should delete only the combining character (vowel/tone mark)

Actual behavior
Both the combining character and the base consonant are deleted

Additional context

• OS: Windows 11 Pro
• Claude Code version: 2.1.173
• The same PowerShell terminal (Windows Terminal) has no issue with Thai input when used normally — the problem is specific to Claude Code's input handler
• Workaround: type Thai text elsewhere and paste into Claude Code