refactor: improve variable naming and add comments for clarity in models and services

tests/api/v1/test_tasks.py

@@ -2,7 +2,7 @@
 
 from __future__ import annotations
 
-from datetime import date, datetime, timedelta, timezone
+from datetime import datetime, timedelta, timezone
 
 import pytest
 from app.models.task import Task
@@ -23,7 +23,7 @@ async def test_create_task_endpoint_creates_task_and_activity(
 ) -> None:
     scenario = await prepare_scenario(session_factory)
     token = make_token(scenario.user_id, scenario.user_email)
-    due_date = (date.today() + timedelta(days=5)).isoformat()
+    due_date = (datetime.now(timezone.utc).date() + timedelta(days=5)).isoformat()
 
     response = await client.post(
         "/api/v1/tasks/",