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/base.html

@@ -14,7 +14,10 @@
         <div class="container">
             <a class="navbar-brand d-flex align-items-center" href="/">
                 <img src="{{ url_for('static', filename='logo.svg') }}" alt="Stegasoo" height="36" class="me-2">
-                <span class="fw-bold title-gold">Stegasoo</span>
+                <span style="position: relative; display: inline-block; margin-top: -14px;">
+                    <span class="fw-bold title-gold">Stegasoo</span>
+                    <span class="badge bg-success" style="position: absolute; font-size: 0.45rem; bottom: -8px; right: 6px;">v4.1</span>
+                </span>
             </a>
             <button class="navbar-toggler" type="button" data-bs-toggle="collapse" data-bs-target="#navbarNav">
                 <span class="navbar-toggler-icon"></span>