Update version badges from v4.0 to v4.1

- Update all v4.0 badges to v4.1 across templates
- Add cute v4.1 badge under Stegasoo title in navbar

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

frontends/web/templates/about.html

@@ -65,7 +65,7 @@
                             <li class="mb-2">
                                 <i class="bi bi-check-circle text-success me-2"></i>
                                 <strong>Channel Keys</strong>
-                                <span class="badge bg-info ms-1">v4.0</span>
+                                <span class="badge bg-info ms-1">v4.1</span>
                                 <br><small class="text-muted">Group/deployment isolation</small>
                             </li>
                         </ul>
@@ -250,7 +250,7 @@
             <div class="card-header">
                 <h5 class="mb-0">
                     <i class="bi bi-broadcast me-2"></i>Channel Keys
-                    <span class="badge bg-info ms-2">v4.0</span>
+                    <span class="badge bg-info ms-2">v4.1</span>
                 </h5>
             </div>
             <div class="card-body">