feat: SEO altyapısı — pre-render, meta tags, blog posts, robots/sitemap

- vite-plugin-prerender yerine Playwright tabanlı post-build pre-render scripti
  (apps/web/scripts/prerender.mjs): 10 public route statik HTML'e dönüştürülüyor
- usePageMeta hook: her public route'da özgün title/description/canonical/OG tags
- index.html: favicon.svg, canonical, OG/Twitter Card, geliştirilmiş title+desc
- apps/web/public/: robots.txt, sitemap.xml (10 URL), favicon.svg
- nginx HSTS header eklendi (Strict-Transport-Security)
- Blog post sayfaları: blog_/$slug.tsx (4 tam yazı, 600-800 kelime)
- blog.tsx: post kartlarına Link eklendi
- Homepage: Schema.org JSON-LD (Organization + SoftwareApplication)
- Footer: placeholder href="#" sosyal linkler kaldırıldı
- deploy.sh + deploy.yml: playwright install chromium + prerender adımı

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

docker/nginx/sites/sase.tr.conf

@@ -2,6 +2,7 @@ server {
     server_name sase.tr;
 
     # Security headers
+    add_header Strict-Transport-Security "max-age=31536000; includeSubDomains" always;
     add_header X-Frame-Options "SAMEORIGIN" always;
     add_header X-Content-Type-Options "nosniff" always;
     add_header X-XSS-Protection "1; mode=block" always;