Implement Multi-Language Support with Language Selection Interface

Enhance the application by introducing multi-language support, allowing users to select their preferred language. The language selection interface should be accessible as follows:

- **Desktop Devices:** Display the language selector on the right side of the navigation bar.
- **Mobile Devices:** Include the language selector within the navigation menu.

**Proposed Folder Structure:**

Organize content files to accommodate multiple languages using the following structure:

- `/data/content-{2_digit_lang_code}/`
- Example: `/data/content-en/` for English content.
- `/data/content/`
- Serve as the fallback directory for default content.

This structure ensures that the application can efficiently manage and serve content in various languages, enhancing the user experience for a diverse audience.