* fix: skip Enter key handling during IME composition
During CJK input (Chinese, Japanese, Korean), pressing Enter while
composing characters should confirm character selection, not send the
message. Check isComposing and keyCode 229 on key events before
handling Enter, matching react-native-web's own IME detection logic.
Fixes#241, #264
* fix: scope IME composition guard to web-only handler
Move isComposing check to top of handleDesktopKeyPress so it never
leaks into cross-platform onKeyPress interfaces. This keeps CJK IME
handling explicit and web-gated.
* refactor: remove IS_WEB alias, use isWeb from platform.ts directly
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Co-authored-by: Mohamed Boudra <boudra.moha@gmail.com>
