Add license key management features and backup functionality

- Updated base template to include a link for license key management.
- Created a new template for license key management with forms for generating and allocating keys, as well as backup options.
- Implemented backup.py for loading and saving licenses to MongoDB, including export and import functionalities.
- Added verify.py for license key verification, user ID generation, and key registration.

Website/templates/base.html

@@ -380,6 +380,7 @@
                                 <a href="{{ url_for('admin_dashboard') }}">Dashboard</a>
                                 <a href="{{ url_for('admin_users') }}">Userverwaltung</a>
                                 <a href="{{ url_for('admin_licenses') }}">Lizenzverwaltung</a>
+                                <a href="{{ url_for('admin_license_keys') }}">Lizenz-Key Verwaltung</a>
                                 <a href="{{ url_for('admin_invoices') }}">Rechnungsverwaltung</a>
                                 <a href="{{ url_for('admin_chats') }}">Admin-Chat</a>
                                 <a href="{{ url_for('admin_tickets') }}">Support-Center</a>