seo: add canonical URL tag

Author: dcoldeira

index.html

@@ -6,6 +6,9 @@
   <title>Bell — Quantum Physics in Plain English | Entangled Code</title>
   <meta name="description" content="Bell is a natural language interface for quantum physics modeling. Describe a quantum problem in plain English — Bell runs real QRL code and returns physics-grounded answers." />
 
+  <!-- Canonical -->
+  <link rel="canonical" href="https://entangledcode.dev/"/>
+
   <!-- Favicon -->
   <link rel="icon" href="favicon.ico" sizes="any"/>
   <link rel="icon" type="image/png" sizes="32x32" href="favicon.png"/>