Task 10: Custom 404 Pages (EN + RU)
Date: 2026-05-14
Status: COMPLETE

Files created:
- src/pages/404.astro
- src/pages/ru/404.astro

Files modified:
- src/i18n/translations.ts (added notFoundTitle, notFoundMessage, backToHome, blog keys)

Build verification:
- npm run build: PASS
- Total pages: 64 (62 existing + 2x 404)
- dist/404.html exists (Astro outputs root 404 as 404.html for static host compatibility)
- dist/ru/404/index.html exists

Content verified:
- EN page contains "Page Not Found"
- RU page contains "Страница не найдена"
- Both pages include breadcrumb back to home, friendly message, and links to home + blog

Key patterns used:
- BaseLayout with title/description props
- Locale detection via Astro.currentLocale
- Translation keys via useT(lang)
- Identical EN/RU template files (locale-aware links computed from lang variable)
- JSON-LD WebPage schema injected via slot="head"