Show available balance on wallet page

app/views/wallet/index.html.erb

@@ -1,14 +1,20 @@
-<section>
-  <h2>Wallet</h2>
-  <p>
-    Send and receive BTC via the Lightning Network.
+<section class="w-full grid grid-cols-1 md:grid-cols-2">
+  <div>
+    <h2>Wallet</h2>
+    <p>
+      Send and receive BTC via the Lightning Network.
+    </p>
+  </div>
+  <p class="font-mono mt-4 md:text-right md:mt-0">
+  <% if @balance %>
+    <span class="text-xl"><%= @balance %> sats</span><br>
+    <span class="text-sm text-gray-500">Available balance</span>
+  <% end %>
   </p>
 </section>
 
 <section>
-  <h3>
-    Blue Wallet
-  </h3>
+  <h3>Blue Wallet</h3>
   <p>
     You can connect
     <%= link_to "Blue Wallet", "https://bluewallet.io",