fix(explorer): add favicon assets

Author: nyusternie

packages/explorer/index.html

@@ -7,6 +7,11 @@
       name="description"
       content="SidΞcoin Explorer — chain-aware block explorer for L1 and Drivechain activity."
     />
+    <link rel="icon" href="/favicon.ico" sizes="any" />
+    <link rel="icon" type="image/png" sizes="16x16" href="/favicon-16x16.png" />
+    <link rel="icon" type="image/png" sizes="32x32" href="/favicon-32x32.png" />
+    <link rel="icon" type="image/png" sizes="48x48" href="/favicon-48x48.png" />
+    <link rel="apple-touch-icon" href="/apple-touch-icon.png" />
     <title>SidΞcoin Explorer</title>
 
     <!-- Analytics -->