Improve i18n support and add missing translations

[neubig]

This PR improves the internationalization (i18n) support in the frontend by:

1. Adding missing translations for all supported languages (zh-CN, zh-TW, ko-KR, de, no, it, pt, es, ar, fr, tr) for:

   • Workspace labels and titles
   • Project and terminal status messages
   • Time-related messages

2. Adding i18n test utilities and translation tests:

   • Added test to verify all translation keys have translations for all supported languages
   • Added test to detect duplicate translation keys
   • Added test utilities for i18n testing

3. Updating UI components to use translations consistently

Fixes #6066 Fixes #4280

Here are examples of the localized screens. I have confirmed that all settings menus, etc. are localized.

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To run this PR locally, use the following command:

docker run -it --rm   -p 3000:3000   -v /var/run/docker.sock:/var/run/docker.sock   --add-host host.docker.internal:host-gateway   -e SANDBOX_RUNTIME_CONTAINER_IMAGE=docker.all-hands.dev/all-hands-ai/runtime:8236300-nikolaik   --name openhands-app-8236300   docker.all-hands.dev/all-hands-ai/openhands:8236300

[neubig]

The localization is very incomplete. For instance, look at these two screens when Japanese is selected as a language:

Only one part of the screen is actually translated in the two main screens. All of the English should be converted into the appropriate language when a different language is selected.

[neubig]

@amanape , apologies that this is a huge PR but hopefully the logic is relatively straightforward.

[neubig]

OK @amanape , I think this is ready for review again!