feat: create config class to replace use of config file in application

src/ui/widgets/MessageCalendar.py

@@ -1,7 +1,7 @@
 from PyQt6 import QtWidgets, QtCore
-from src.backend.database import Database
 from PyQt6.QtCore import QDate
 from PyQt6.QtGui import QColor, QPen
+from src.backend import Database
 import darkdetect
 from icecream import ic