feat: added validation for timer constructor, added function to calculate hours, minutes and seconds from entered minutes

kawai_focus/screens/validators_fields.py

@@ -0,0 +1,5 @@
+def validate_title(obj, text):
+    """Валидатор поля title"""
+    
+    if not text:
+        obj.ids.title_error.text = 'Введите название!'