Add OxaPay to services list

Introduces OxaPay as a listed service provider. This update includes the addition of the OxaPay icon and link, formatted consistently with existing entries. No logic or functional behavior has been modified; this change is solely presentational.

Author: kevin-san0

views/index.html.erb

@@ -491,6 +491,9 @@
         <div class="col-sm-4 col-md-3 vertical-align">
           <a href="https://coingate.com/" target="_blank"><img loading="lazy" alt="CoinGate" src="/img/services/coingate.webp"></a>
         </div>
+        <div class="col-sm-4 col-md-3 vertical-align">
+          <a href="https://www.oxapay.com" target="_blank"><img loading="lazy" alt="OxaPay" src="/img/services/oxapay.webp"></a>
+        </div>
         <div class="col-sm-4 col-md-3 vertical-align">
           <a href="https://gourl.io/" target="_blank"><img loading="lazy" alt="GoUrl" src="/img/services/gourl.webp"></a>
         </div>