Add password change functionality and profile image upload

- Add profile_image field to Profile model with default value
- Update profile edit route to handle profile image file uploads
- Add password change route with validation in auth module
- Create change password template with form
- Update profile template to include image upload with preview
- Add password change link to admin sidebar
- Update homepage to use dynamic profile image from database

templates/admin/base.html

@@ -100,6 +100,9 @@
                 <i class="fas fa-share-alt me-2"></i>Link Social
             </a>
             <hr class="border-white my-3 mx-3">
+            <a href="{{ url_for('auth.change_password') }}" class="{% if request.endpoint == 'auth.change_password' %}active{% endif %}">
+                <i class="fas fa-key me-2"></i>Cambia Password
+            </a>
             <a href="{{ url_for('route_home.home') }}" target="_blank">
                 <i class="fas fa-external-link-alt me-2"></i>Visualizza Sito
             </a>