feat(i18n): expand Explorer to 17 languages (incl. Catalan) and RTL support

[NateIsern]

Motivation

• Broaden the app's internationalization coverage to the world's most-spoken languages (and Catalan) so the Explorer UI can be fully localized and selectable at runtime.
• Ensure the runtime and UI behave correctly for additional locales, including right-to-left (RTL) languages, and keep date formatting and feedback messages localized.

Description

• Added nine complete translation catalogs and registered them in the loader, expanding supported locales from 8 to 17 by adding ca, hi, ar, bn, pt, id, ur, tr, and vi and their src/messages/*.json files and integrating them into src/lib/i18n.ts.
• Extended the Locale type, SUPPORTED_LOCALES list, and messagesByLocale map, and added automatic document lang/dir synchronization with RTL detection for Arabic and Urdu via a syncDocumentLanguage helper.
• Localized the language-change toast by using useTranslations('common') in src/components/language-selector.tsx so feedback uses the active locale's template instead of a fixed English string.
• Expanded date-fns locale mappings used by RelativeTime and GithubCard to include the new locales and remapped Urdu to use Arabic date locale where appropriate so relative-time formatting follows the active locale.
• Updated src/lib/i18n.test.ts with assertions that at least 15 languages are available (including Catalan) and that RTL direction is applied for Arabic/Urdu.

Testing

• Ran the i18n smoke tests with npm test -- --run src/lib/i18n.test.ts and all tests passed (11 tests passing).
• Executed npm run typecheck (TypeScript project build) and it completed successfully.
• Built the production output with npm run build (Vite) and the build completed successfully.
• Verified catalog completeness and placeholder consistency with a Python verification script that confirmed 17 complete catalogs, 1,076 keys per catalog, and matching placeholders.

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Codex Task

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