[Bug] macOS notifications garble non-ASCII (Korean) characters

Bug Description

macOS desktop notifications from Claude Code display garbled/broken Korean (and likely other non-ASCII/CJK) characters. The text in the Claude Code terminal itself renders correctly, but the macOS notification center shows corrupted characters.

Steps to Reproduce

1. Use Claude Code Desktop app on macOS
2. Trigger any action that produces Korean text output (e.g., a cron job creation response in Korean)
3. Observe the macOS notification

Expected Behavior

Korean text should render correctly in macOS notifications, e.g.:

크론 작업 다시 생성했습니다. Job ID: 10d29099, 5분마다 새로운 PR 리뷰 요청을 체크합니다.

Actual Behavior

Korean characters are garbled/broken in the notification:

<img width="704" height="192" alt="Image" src="https://github.com/user-attachments/assets/4be324a7-43cb-4835-93a2-7cad4bc534bc" />

The notification shows broken characters like:

? 山: ? ? ? ㅐ ??깊?듬??. Job ID: 10d29099, 5 遺_留 ?? ?濡?? PR 由ㅂ력 ?泥?

Root Cause Hypothesis

Claude Code uses osascript (display notification) to send macOS notifications (see #41511). The osascript invocation likely does not properly handle UTF-8 encoded Korean text, causing the characters to be garbled. This may be due to:

• Missing UTF-8 encoding when passing text to osascript
• Shell escaping issues stripping multi-byte characters

Related Issues

• #41511 — macOS notifications appear from "Script Editor" instead of "Claude Code" (same osascript notification mechanism)

Environment

• macOS Sequoia (Darwin 24.3.0)
• Claude Code Desktop App
• System language includes Korean
• Apple Silicon Mac (M-series)