1. Feat(Security): Patched vulnerabilities exposed by Zaproxy scan.

a. Added anti-clickjacking header
 b. Added robots.txt
 c. Added sitemap.xml
 d. Added cache-control header
2. Feat(SEO): Added yandex verification meta tag.

index.html

@@ -4,6 +4,11 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1.0">
     <title>Teddy</title>
+    <!-- SEO -->
+    <meta name="yandex-verification" content="6d6eae9d533ef680" />
+    <!-- Security -->
+    <meta http-equiv="X-Frame-Options" content="SAMEORIGIN">
+    <meta http-equiv="Cache-Control" content="no-store, no-cache, must-revalidate">
     <style>
         /* Modern CSS reset and variables */
         :root {