Add Google Calendar integration with display manager. Includes calendar manager implementation, configuration updates, and registration script.

src/display_manager.py

@@ -5,6 +5,7 @@ from typing import Dict, Any, List, Tuple
 import logging
 import math
 from .weather_icons import WeatherIcons
+from .calendar_manager import CalendarManager
 import os
 
 # Get logger without configuring
@@ -29,6 +30,9 @@ class DisplayManager:
         self._load_fonts()
         logger.info("Font loading completed in %.3f seconds", time.time() - font_time)
         
+        # Initialize managers
+        self.calendar_manager = CalendarManager(self.matrix, self.current_canvas, self.config)
+        
     def _setup_matrix(self):
         """Initialize the RGB matrix with configuration settings."""
         setup_start = time.time()