Add Spotify integration with improved token management and user interface

- Implemented Spotify OAuth handling in spotify_client_manager.py to ensure valid access tokens for users.
- Created helper functions in spotify_helper.py for refreshing tokens and retrieving user information.
- Developed manage_spotify.html template for connecting and managing Spotify accounts, displaying connection status and token information.
- Added logging for token management processes to enhance debugging and monitoring.
- Introduced a debug client for Spotify interactions to facilitate easier testing and development.

musicround/templates/round_detail.html

@@ -538,17 +538,7 @@
         
         // Close toast button event
         toastCloseBtn.addEventListener('click', hideToast);
-        
-        // Process flash messages from server
-        {% with messages = get_flashed_messages(with_categories=true) %}
-            {% if messages %}
-                {% for category, message in messages %}
-                    showToast('{{ message|safe }}', '{{ category }}');
-                {% endfor %}
-            {% endif %}
-        {% endwith %}
-        
-        // Process email error if any
+          // Process email error if any
         {% if email_error %}
             showToast('{{ email_error }}', 'error');
         {% endif %}