style: Add tutorial management features with video display and admin upload functionality

Website/templates/base.html

@@ -527,6 +527,7 @@
                     <a class="nav-user-link" href="{{ url_for('admin_tickets') }}">Support-Center</a>
                     <a class="nav-user-link" href="{{ url_for('admin_system_tools') }}">System-Tools</a>
                 {% elif 'username' in session %}
+                    <a class="nav-user-link" href="{{ url_for('my_tutorials') }}">📚 Tutorials</a>
                     <a class="nav-user-link" href="{{ url_for('my_invoices') }}">Meine Rechnungen</a>
                     <a class="nav-user-link" href="{{ url_for('my_instance_management') }}">Meine Instanz</a>
                     <a class="nav-user-link" href="{{ url_for('user_chat') }}">Chat mit Admin</a>
@@ -557,6 +558,7 @@
                     <details class="nav-dropdown">
                         <summary class="nav-btn">Nutzerbereich</summary>
                         <div class="dropdown-menu">
+                            <a href="{{ url_for('my_tutorials') }}">📚 Tutorials</a>
                             <a href="{{ url_for('my_invoices') }}">Meine Rechnungen</a>
                             <a href="{{ url_for('my_instance_management') }}">Meine Instanz</a>
                             <a href="{{ url_for('user_chat') }}">Chat mit Admin</a>