style(ink): update ink theme templates

Co-Authored-By: Claude <noreply@anthropic.com>

themes/ink/mail/repo/issue/default.tmpl

@@ -80,7 +80,7 @@
           <img src="{{AppUrl}}assets/img/favicon.png" alt="logo" width="24" height="24" class="email-logo" />
           <span class="email-brand">{{AppName}}</span>
           <br />
-          <span style="font-size:11px;color:#888;font-style:italic;">Gitea Mail Templates</span>
+          <span style="font-size:11px;color:#888;font-style:italic;">Git with a cup of tea</span>
 
         </td>
       </tr>