This commit introduces Japanese as a supported language in the web application.
Key changes include:
- Addition of a new `ja` locale with 15 translated JSON resource files, making the application accessible to Japanese-speaking users.
- Update of the `LanguageSwitcher.tsx` component to include '日本語' in the language selection dropdown menu, allowing users to switch to the new language.
- The localization files were added by creating a new `ja` directory under `web-app/src/locales` and translating the content from the `en` directory.
Co-authored-by: google-labs-jules[bot] <161369871+google-labs-jules[bot]@users.noreply.github.com>
