Add logo.png and favicon.ico, update nav/footer/JSON-LD

src/components/Footer.jsx

@@ -9,7 +9,7 @@ export default function Footer() {
   return (
     <footer className="bg-slate-900 text-slate-400 py-10">
       <div className="max-w-6xl mx-auto px-4 sm:px-6 flex flex-col md:flex-row items-center justify-between gap-4">
-        <span className="text-white font-semibold">Сисадмингрупп</span>
+        <img src="/logo.png" alt="Сисадмингрупп" className="h-7 w-auto brightness-0 invert" />
         <span className="text-sm">{year} © {t('footer.rights')}</span>
         <div className="flex flex-wrap justify-center gap-x-6 gap-y-1 text-sm">
           {phones.map((p, i) => (

src/components/Navigation.jsx

@@ -22,8 +22,8 @@ export default function Navigation() {
   return (
     <header className={`fixed top-0 left-0 right-0 z-50 transition-all duration-300 ${scrolled ? 'bg-white/95 backdrop-blur shadow-sm' : 'bg-transparent'}`}>
       <div className="max-w-6xl mx-auto px-4 sm:px-6 h-16 flex items-center justify-between">
-        <a href="#" className="text-xl font-bold text-slate-900 tracking-tight">
-          Сисадмингрупп
+        <a href="#" className="flex items-center">
+          <img src="/logo.png" alt="Сисадмингрупп" className="h-8 w-auto" />
         </a>
 
         {/* Desktop nav */}