fix: Hero-Video als Vollbild über gesamte Hero-Section

Video füllt jetzt die komplette Hero-Section (88vh) statt nur den
700px-breiten Slide-Container. Ein-/Ausblenden per CSS-Transition
(0.8s) gekoppelt an den aktiven Slide (nur bei Slide 0 sichtbar).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

vorschau/index.html

@@ -81,6 +81,11 @@
     <!-- Hero Section -->
     <section class="hero" id="hero">
         <div class="hero-overlay"></div>
+        <div class="hero-fullscreen-video visible" id="hero-fullscreen-video">
+            <video autoplay muted loop playsinline>
+                <source src="videos/hero-slide-1-monitoring.mp4" type="video/mp4">
+            </video>
+        </div>
         <div class="container hero-content">
             <div class="hero-brand">
                 <h1 class="hero-title">AegisSight Monitor</h1>
@@ -89,12 +94,7 @@
 
             <div class="hero-slider" role="region" aria-label="Produktvorteile" aria-live="polite">
                 <!-- Slide 1: Echtzeit-Monitoring -->
-                <div class="hero-slide hero-slide-video active" data-slide="0">
-                    <div class="hero-slide-video-bg">
-                        <video autoplay muted loop playsinline>
-                            <source src="videos/hero-slide-1-monitoring.mp4" type="video/mp4">
-                        </video>
-                    </div>
+                <div class="hero-slide active" data-slide="0">
                     <div class="hero-slide-inner">
                         <div class="hero-slide-text-col">
                             <span class="hero-slide-label">Echtzeit-Monitoring</span>