Feature request: Japanese (and other language) localization for VS Code extension UI

The Claude Code VS Code extension's own UI elements (e.g., the "Modes" menu: Manual / Edit automatically / Plan / Auto, and the "Effort" selector) are hardcoded in English and are not affected by VS Code's display language setting or language pack extensions (e.g., ms-ceintl.vscode-language-pack-ja).

**Describe the solution you'd like**
Add localization (l10n/nls) support for the extension's UI strings, respecting VS Code's configured display language.

**Additional context**
Checked extension version: anthropic.claude-code 2.1.263. No nls/l10n/locale files were found bundled with the extension

Start by locating the Claude Code VS Code extension UI that renders the Modes menu and Effort selector, then inspect how those strings are currently defined. Check how the extension can use VS Code's configured display language and language packs. Done means the extension UI strings are localized and respond to the configured display language.

Written by the indexing model from the issue text.