Restrict Train navbar link to admin users only

- Wrap Train link with admin role check in base.html
- Regular users can no longer see/access the Train page from navbar
- Maintains existing admin access to training functionality

templates/base.html

@@ -31,7 +31,9 @@
             <nav class="nav">
                 <a href="/dashboard" {% if active_page == 'dashboard' %}class="active"{% endif %}>Dashboard</a>
                 <a href="/analyze" {% if active_page == 'analyze' %}class="active"{% endif %}>Analyze</a>
+                {% if user.get('role') == 'admin' %}
                 <a href="/train" {% if active_page == 'train' %}class="active"{% endif %}>Train</a>
+                {% endif %}
                 <a href="/history" {% if active_page == 'history' %}class="active"{% endif %}>History</a>
                 {% if user.get('role') == 'admin' %}
                 <a href="/api_tokens" {% if active_page == 'api_tokens' %}class="active"{% endif %}>API Tokens</a>