add meta tags and logo for social media

docs/_layouts/default.html

@@ -4,6 +4,29 @@
     <meta charset="UTF-8">
     <meta name="viewport" content="width=device-width, initial-scale=1">
 
+    <meta name="description" content="A production-inspired distributed systems reference implementation using .NET 10, Azure, microservices, Azure Service Bus, Azure SQL, Azure Entra ID and modern DevOps practices.">
+    <meta name="keywords" content="Distributed Systems,Microservices,.NET 10,C#,Azure,Cloud Architecture,Azure Service Bus,Azure SQL,Azure Entra ID,Azure App Service,API Gateway,YARP,CQRS,Domain Driven Design,DevOps,Azure DevOps,Bicep,Docker,Cloud Native,Reference Architecture">
+
+    <!--Open Graph (LinkedIn/Facebook)-->
+    <meta property="og:type" content="website">
+    <meta property="og:title" content="Distributed Systems Reference Project">
+    <meta property="og:description" content="Production-inspired distributed systems architecture built with .NET 10 and Azure. Demonstrates microservices, cloud-native design, messaging, security and DevOps best practices.">
+    <meta property="og:url" content="https://distributed-systems.ausdatatech.com.au/">
+    <meta property="og:image" content="https://distributed-systems.ausdatatech.com.au/assets/images/social-preview.png">
+    <meta property="og:site_name" content="Aus Data Tech">
+
+    <!--Twitter/X Card-->
+    <meta name="twitter:card" content="summary_large_image">
+    <meta name="twitter:title" content="Distributed Systems Reference Project">
+    <meta name="twitter:description" content="Production-inspired distributed systems built with .NET 10 and Azure.">
+    <meta name="twitter:image" content="https://distributed-systems.ausdatatech.com.au/assets/images/social-preview.png">
+
+    <!--Canonical URL-->
+    <link rel="canonical" href="https://distributed-systems.ausdatatech.com.au/">
+
+    <!--Author-->
+    <meta name="author" content="Philip Todd">
+
     <title>{{ page.title }} | {{ site.title }}</title>
 
     <link rel="stylesheet" href="{{ '/assets/css/styles.css' | relative_url }}">