feat(blog+categories): Wave 3-5 — blog infrastructure, categories, content, navigation

- Install @astrojs/rss and setup content collections (blog + generators)
- Create BlogLayout with BlogPosting schema, article OG tags, prev/next nav
- Create blog post pages EN/RU ([slug].astro) with dynamic routing
- Create blog index pages EN/RU with post cards and filtering
- Create RSS feeds EN/RU with auto-discovery links
- Create generator category pages EN/RU (5 categories each)
- Add category navigation pills to homepage
- Create Breadcrumbs, RelatedGenerators, RelatedPosts components
- Add breadcrumbs to GeneratorLayout and BlogLayout
- Wire RelatedGenerators into GeneratorLayout
- Wire RelatedPosts into blog post pages
- Create 8 EN + 8 RU blog post templates with placeholder content
- Add blog link to LanguageSwitcher navigation
- Add category and blog translation keys

package.json

@@ -15,6 +15,7 @@
     "format:check": "prettier --check ."
   },
   "dependencies": {
+    "@astrojs/rss": "^4.0.18",
     "@astrojs/sitemap": "^3.2.1",
     "@tailwindcss/vite": "^4.0.0",
     "astro": "^4.16.0",