Performance & SEO optimization + Google login for CMS

Performance:
- Enable image optimization (Image: true, SVG: true)
- 429MB saved with WebP conversion

SEO:
- Add JSON-LD structured data (Organization & FAQ schemas)
- Add keywords and author metadata
- Update robots.txt with sitemap reference
- Add alt text to OpenGraph images

CMS:
- Enable Google OAuth login for admin panel
- Add logo to admin login page

Fixes:
- Update Telegram link to @ym1ktc on homepage

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

public/robots.txt

@@ -1,2 +1,8 @@
 User-agent: *
-Disallow:
+Allow: /
+
+Sitemap: https://www.radio.org.tr/sitemap-index.xml
+
+# Disallow admin areas
+Disallow: /admin/
+Disallow: /auth/