seo: GA4, breadcrumbs JSON-LD, IndexNow post-deploy, llms.txt

- Add GA4 (G-C9J0D8FFH3) to root layout alongside Yandex.Metrika
- Add BreadcrumbList JSON-LD schema to all inner pages
- Add scripts/indexnow.mjs — submits 30 URLs to IndexNow + Yandex on deploy
- Add indexnow to postdeploy step in package.json
- Update llms.txt with all 8 services and new pages (about/clients/partners)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/app/[lang]/about/page.tsx

@@ -1,5 +1,6 @@
 import type { Metadata } from 'next'
 import { getDictionary, LOCALES, type Locale } from '@/lib/i18n'
+import { breadcrumbSchema } from '@/lib/breadcrumbs'
 import AboutSection from '@/components/sections/AboutSection'
 
 export function generateStaticParams() {
@@ -37,9 +38,14 @@ export default async function AboutPage({ params }: { params: Promise<{ lang: st
   const { lang: langStr } = await params
   const lang = langStr as Locale
   const d = getDictionary(lang)
+  const isRu = lang === 'ru'
   return (
     <div className="pt-16">
       <AboutSection d={d} standalone />
+      <script type="application/ld+json" dangerouslySetInnerHTML={{ __html: JSON.stringify(breadcrumbSchema([
+        { name: isRu ? 'Главная' : 'Home', url: `https://sag24.ru/${lang}/` },
+        { name: isRu ? 'О компании' : 'About', url: `https://sag24.ru/${lang}/about/` },
+      ])) }} />
     </div>
   )
 }