fix(seo): Wave 1 — fix critical SEO gaps

- Fix duplicate faq/ruFaq keys in dice.json, list.json, colors.json
- Add <main> landmarks to about/privacy pages (EN + RU)
- Move YandexRTB after <main> on homepage
- Add x-default hreflang to BaseLayout
- Configure sitemap i18n with hreflang alternates
- Add Open Graph + Twitter Card meta tags
- Create default OG image (1200x630)

astro.config.mjs

@@ -4,7 +4,15 @@ import sitemap from "@astrojs/sitemap";
 
 export default defineConfig({
   site: "https://randify.pro",
-  integrations: [sitemap()],
+  integrations: [sitemap({
+    i18n: {
+      defaultLocale: "en",
+      locales: {
+        en: "en-US",
+        ru: "ru-RU",
+      },
+    },
+  })],
   vite: {
     plugins: [tailwindcss()],
   },