Conversation titles are generated in English despite language: "japanese" setting

Description

Conversation/session titles are automatically generated in English even when the language setting is configured to "japanese" in ~/.claude/settings.json.

Configuration

settings.json:

{
  "language": "japanese",
  ...
}

CLAUDE.md also explicitly instructs:

- 日本語でのコミュニケーションを基本とする
- 会話のタイトル（件名）も必ず日本語で生成すること
- 英語のタイトルは使わない

Current Behavior

• Responses within conversations are correctly in Japanese
• However, auto-generated conversation titles in the sidebar are often in English
• Examples of English titles that should be Japanese:
• "Review past project experiences"
• "Auto-update monthly form options da..."
• "Add user authentication to web applic..."

Expected Behavior

When language is set to "japanese", conversation titles should also be generated in Japanese.

Environment

• Platform: macOS (Darwin 25.3.0)
• Claude Code (Desktop app)