Fix calendar URL is entered just once

jobs/tasks.py

@@ -20,6 +20,7 @@ class TasksJob(Job):
         return "UKOLY DNE"
 
     def configure(self):
+        if not os.path.exists('calendar_url.txt'):
             print("\n--- Configure Calendar URL ---")
             print("To find your Google Calendar URL:")
             print("1. Go to Settings > Select Calendar > Integrate calendar")
@@ -32,6 +33,8 @@ class TasksJob(Job):
                 with open('calendar_url.txt', 'w') as f:
                     f.write(url)
                 print("URL saved.")
+        else:
+            print("\nCalendar URL is already configured (delete calendar_url.txt to reset).")
         
         print("-" * 30)
         try: