fix: Flash of default language before applying user preference #126

When a user's system or preferred language is not the default (en) (e.g., ar), the page initially renders in English and then re-renders in the expected language. This causes a noticeable flash of incorrect content and potentially hydration mismatches.

Tasks

• Investigate the initialization logic in the language provider or layout.
• Implement server-side language detection (via Accept-Language header, cookies, or Next.js middleware) so the initial HTML matches the user's preference.
• Update the <html> tag's lang and dir attributes to be set correctly on the first server render.