feat(i18n): add Bahasa Indonesia translations and help documentation

[teguh02]

📋 Summary

This PR adds Indonesian (Bahasa Indonesia) locale support to Nginx Proxy Manager, including UI translations and Indonesian-language help documentation.

Bahasa Indonesia is the national language of Indonesia and is widely used by millions of users across Southeast Asia. Adding Indonesian support improves accessibility for Indonesian-speaking users and contributes to broader localisation efforts in open-source projects.

🎯 Changes

New Files Added

Translation file:

• frontend/src/locale/src/id.json

Help documentation (Indonesian / Bahasa Indonesia):

• frontend/src/locale/src/HelpDoc/id/AccessLists.md
• frontend/src/locale/src/HelpDoc/id/Certificates.md
• frontend/src/locale/src/HelpDoc/id/DeadHosts.md
• frontend/src/locale/src/HelpDoc/id/ProxyHosts.md
• frontend/src/locale/src/HelpDoc/id/RedirectionHosts.md
• frontend/src/locale/src/HelpDoc/id/Streams.md
• frontend/src/locale/src/HelpDoc/id/index.ts

Modified Files

• frontend/check-locales.cjs – Added Indonesian locale configuration
• frontend/src/locale/IntlProvider.tsx – Registered Indonesian locale
• frontend/src/locale/src/HelpDoc/index.tsx – Registered Indonesian help documentation
• frontend/src/locale/src/lang-list.json – Added Indonesian display name

🌐 Locale Details

• Locale Code: id
• Language Tag: id-ID
• Language Name: Bahasa Indonesia (Indonesian)
• Display Name: Bahasa Indonesia
• Flag Code: ID (Indonesia)
• Translation Coverage: UI strings translated; help documentation fully translated

✨ Features

• ✅ Indonesian (Bahasa Indonesia) UI localisation
• ✅ All help documentation translated into Indonesian
• ✅ Follows existing locale structure and implementation patterns
• ✅ No breaking changes
• ✅ Backward-compatible with existing locales

💡 Additional Notes

The translations aim to use formal, clear, and standard Indonesian, prioritising consistency with existing UI terminology and avoiding overly literal translations where they would reduce readability.

Changes were implemented by following the guidance in frontend/src/locale/README.md and referencing existing locale implementations.

⚠️ Note: A local Docker-based dev instance was not spun up for this PR. The contribution focuses on correctness, consistency, and completeness of the locale files.

🙏 Acknowledgments

Thank you for considering this contribution. Adding Indonesian language support helps broaden accessibility for Indonesian-speaking users and reflects the linguistic diversity of the Nginx Proxy Manager community.