Original-Logo von olzinger.de in der Navigation

- Platzhalter-Logo (Thermostat-Bogen) durch das echte Firmenlogo ersetzt,
  auf weißem Schild, auf allen Seiten inkl. 404
- Navigationsleiste am Desktop etwas höher für bessere Lesbarkeit
- Schema.org-Logo, OG-Vorlage und README angepasst

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

tools/og-template.html

@@ -21,13 +21,8 @@
 <body>
 <div class="og" id="og">
   <canvas data-thermal></canvas>
-  <a class="logo og__logo" style="color:#F3EFE8">
-    <svg class="logo__mark" viewBox="0 0 40 40" style="width:52px;height:52px">
-      <defs><linearGradient id="g-logo" x1="0" y1="0" x2="1" y2="0"><stop offset="0" stop-color="#2E9BEF"/><stop offset=".55" stop-color="#C2456B"/><stop offset="1" stop-color="#FF6A2B"/></linearGradient></defs>
-      <path d="M11.97 31.47A14 14 0 1 1 28.03 31.47" fill="none" stroke="url(#g-logo)" stroke-width="5.5" stroke-linecap="round"/>
-      <circle cx="20" cy="20" r="3.4" fill="currentColor"/>
-    </svg>
-    <span class="logo__text"><span class="logo__word" style="font-size:28px">Olzinger</span><span class="logo__sub" style="font-size:14px">Haustechnik</span></span>
+  <a class="logo og__logo">
+    <img class="logo__img" src="../assets/img/olzinger-logo.png" alt="" width="260" height="125">
   </a>
   <h1 class="og__title">
     <span>Wärme<i style="background:#FF6A2B;box-shadow:0 0 .28em rgba(255,106,43,.75)"></i></span>