Redesign public language-learning experience

[fdaei]

Summary

• redesign the public landing experience with a stronger SaaS-style hero, trust strip, clearer learning journey, richer feature storytelling, proof section, improved FAQ, and conversion-focused final CTA
• rebuild the public header and footer hierarchy, responsive navigation, active states, authentication actions, trust elements, and a safe built-in wordmark fallback
• upgrade language, course, and teacher listing pages with consistent page heroes, supporting metrics, stronger information hierarchy, and clearer calls to action
• improve reusable language/course/teacher cards with product metadata, hover/focus states, responsive behavior, and more consistent visual density
• preserve the website-builder configuration and existing route/functionality behavior
• distinguish a missing navigation configuration from an intentionally empty navigation, so fresh databases retain the default public menu

Design system

• consolidated public spacing, type scale, radii, shadows, surfaces, button states, card patterns, and responsive breakpoints
• added keyboard-visible focus styling and reduced-motion behavior
• kept Persian RTL and English LTR layouts supported

Validation

• ✅ web TypeScript check
• ✅ web ESLint
• ✅ production Next.js build
• ✅ Prettier and diff checks
• ✅ targeted public-shell, routing, course-directory, and teacher-filter tests (12/12)
• ⚠️ full web suite: 184/185 tests pass; the existing admin-teachers-manager.spec.tsx mock does not provide apiField. The failing admin file is outside this PR and was not modified.

QA note

The redesign was checked against the supplied current-state screenshots and validated through the production build and relevant automated tests.