Add two new white-background themes with distinct design languages:
- Clean: soft blue accents, rounded cards, gradient CTA section
- Corporate: slate/professional palette, sharp borders, structured layout
Both themes include full nav (with topup), LanguageSwitch, FadeContent
animations, model grid, package cards, and responsive mobile menu.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
