feat(i18n): localize main page and enable i18n for homepage texts

- Updated index.tsx to use <Translate> and translate() for all main texts (title, subtitle, CTA, description) — now fully i18n-ready.
- Added new translation files (code.json, navbar.json, footer.json, etc.) to support Russian language for homepage and UI.
- Enables seamless language switching and correct translations of homepage elements.

website/i18n/ru/docusaurus-plugin-content-docs/current.json

@@ -0,0 +1,14 @@
+{
+  "version.label": {
+    "message": "Next",
+    "description": "The label for version current"
+  },
+  "sidebar.tutorialSidebar.category.Core Concepts": {
+    "message": "Core Concepts",
+    "description": "The label for category Core Concepts in sidebar tutorialSidebar"
+  },
+  "sidebar.tutorialSidebar.category.Advanced Features": {
+    "message": "Advanced Features",
+    "description": "The label for category Advanced Features in sidebar tutorialSidebar"
+  }
+}