feat(i18n): Add Khmer Language Translation

[samnangdeoun]

🔗 Linked issue

resolves #98

❓ Type of change

• 📖 Documentation (updates to the documentation or readme)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This pull request adds Khmer (km) language support to the project.

• Introduced translation files for Khmer.
• Ensured all relevant UI strings have Khmer equivalents.
• Verified that the i18n setup recognizes Khmer (km) as an available locale.

Why this change is needed:

• Expands accessibility for Khmer-speaking users.
• Aligns with the project’s internationalization goals.
• Completes the request tracked in issue New Support for Language Translation (KHMER) #98.

Impact:

• This is a non-breaking change.
• No existing functionality is affected; it only adds a new translation option.