Add frontend landing site and OG assets

Add full frontend landing site for VKify: new English and Russian READMEs, many public assets (OG theme images, site preview, wallpapers, videos) and a generate-og script to produce per-theme og:image files. Introduce pages, components, hooks and utils for themes, wallpapers, previews, install/uninstall flows, SEO and theme sharing (new pages/components under src/, plus new data files). Update app entry, styles and config to support pre-rendering/hydration and SEO; adjust robots.xml and sitemap. package.json and package-lock updated; removed obsolete public/404.html. This change brings the complete static/site assets and app code required to build and prerender the landing site.

Author: Rianvy

.github/assets/logo.png

@@ -5,7 +5,8 @@
   "type": "module",
   "scripts": {
     "dev": "vite",
-    "build": "vite build",
+    "generate-og": "node scripts/generate-og.js",
+    "build": "node scripts/generate-og.js && vite build",
     "preview": "vite preview"
   },
   "dependencies": {
@@ -26,6 +27,6 @@
     "autoprefixer": "^10.4.16",
     "postcss": "^8.4.31",
     "tailwindcss": "^3.3.5",
-    "vite": "^5.0.0"
+    "vite": "^7.0.0"
   }
 }