Korean (CJK) IME input broken - jamo not composed into syllables

Bug Description

Korean IME input does not work in Claude Code's interactive prompt.
Individual jamo (consonants/vowels) are entered separately instead of
being composed into syllables.

Example: typing "한글" results in "ㅎㅏㄴㄱㅡㄹ"

Environment

• Claude Code: 2.1.81
• OS: Ubuntu Linux 6.17.0-19-generic
• Locale: ko_KR.UTF-8
• Terminals tested: gnome-terminal, tmux, iPad Termius (all affected)

Steps to Reproduce

1. Set locale to ko_KR.UTF-8
2. Run claude in interactive mode
3. Type Korean at the prompt
4. Jamo are not composed into syllables

Expected

ㅎ+ㅏ+ㄴ = 한 (normal IME composition)

Actual

ㅎㅏㄴ (raw jamo, no composition)

Root Cause

Claude Code's raw/cbreak terminal mode (Ink/React) captures keystrokes before OS IME can compose them.

Impact

Affects all CJK languages requiring IME (Korean, Chinese, Japanese).