feat: Optimize i18n and update Arabic content

- Update Arabic logo initials to 'خ ش' with proper RTL styling
- Add comprehensive Arabic tagline highlighting full-stack expertise
- Expand Key Highlights to 9 items across all languages (en, de, fr, ar)
- Remove outdated focus areas (AI, Web Dev, Data Science) from skills section
- Clean up documentation files and consolidate guides
- Update translation validation scripts
- Optimize Core Technical Skills section structure
- Remove expertInAI field from dynamic content (not relevant to expertise)
- Update TypeScript interfaces for cleaner type definitions

Author: kcharfi24