[FEATURE] Generate session titles in the user's conversation language (e.g. Japanese)

Problem Statement

Auto-generated session titles are always in English, even when the user converses with Claude entirely in Japanese and has "language": "japanese" set in settings.json. For non-English users the session list (CLI session picker and VSCode extension) becomes hard to scan, and they must manually /rename every single session to get readable titles.

Proposed Solution

Generate the auto session title in the language actually used in the conversation, or at least respect the existing "language" setting in settings.json when generating titles. A dedicated setting (e.g. "sessionTitleLanguage") would also work.

Alternative Solutions

Manually renaming each session with /rename or starting with claude -n "name". This works but has to be repeated for every session and is easy to forget.

Priority

Medium - Would be very helpful

Feature Category

Configuration and settings

Use Case Example

A Japanese user runs Claude Code daily, conversing entirely in Japanese. With Japanese session titles, the session picker would be scannable at a glance instead of showing English summaries of Japanese conversations.