[FEATURE] Respect conversation language for session titles in VSCode extension

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

I use Claude Code's VSCode extension entirely in Japanese — all my prompts and all responses are in Japanese. However, the session list in the left sidebar shows auto-generated titles in English (e.g. "Review GitHub integration security", "Check remaining tasks").

This makes it very hard to scan the session list and find a past conversation at a glance. I have to open sessions one by one to recall what they were about, because the English summary doesn't match the Japanese content in my memory.

This is a significant friction point for non-English users who rely on the session list to navigate their work history.

Proposed Solution

Generate session titles in the same language as the conversation.

Ideal UX:

• Detect the primary language of the conversation (first few user messages) and generate the title in that language.
• Optionally, expose a setting like claude-code.sessionTitleLanguage: "auto" | "en" | "ja" | ... so users can force a specific language.
• As a minimum fallback, surface an easy inline rename affordance (pencil icon on hover) so users can fix titles themselves without digging into menus.

Alternative Solutions

Generate session titles in the same language as the conversation.

Ideal UX:

• Detect the primary language of the conversation (first few user messages) and generate the title in that language.
• Optionally, expose a setting like claude-code.sessionTitleLanguage: "auto" | "en" | "ja" | ... so users can force a specific language.
• As a minimum fallback, surface an easy inline rename affordance (pencil icon on hover) so users can fix titles themselves without digging into menus.

Priority

Low - Nice to have

Feature Category

Other

Use Case Example

Generate session titles in the same language as the conversation.

Ideal UX:

• Detect the primary language of the conversation (first few user messages) and generate the title in that language.
• Optionally, expose a setting like claude-code.sessionTitleLanguage: "auto" | "en" | "ja" | ... so users can force a specific language.
• As a minimum fallback, surface an easy inline rename affordance (pencil icon on hover) so users can fix titles themselves without digging into menus.

Additional Context

_No response_