chore: resolve final review findings

Co-authored-by: OpenAI/GPT-5.6-Terra <vibecoder@antoineve.me>
Co-authored-by: DeepSeek/DeepSeek-v4-Pro <vibecoder@antoineve.me>
Co-authored-by: DeepSeek/DeepSeek-v4-Flash <vibecoder@antoineve.me>

tests/test_time_calc.py

@@ -1,8 +1,14 @@
+from datetime import date
+from datetime import time as dtime
+
 from app.business.time_calc import (
+    count_day_types,
     minutes_to_str,
+    monthly_stats,
     week_balance_minutes,
     work_minutes_reference,
 )
+from app.models import TimeSlot, WorkEntry
 
 
 def test_minutes_to_str_basic():
@@ -42,13 +48,6 @@ def test_week_balance_negative():
     assert week_balance_minutes(2200, 2325) == -125
 
 
-from datetime import date
-from datetime import time as dtime
-
-from app.business.time_calc import count_day_types, monthly_stats
-from app.models import TimeSlot, WorkEntry
-
-
 def test_count_day_types_basic():
     entries = [
         WorkEntry(date=date(2025, 1, 2), day_type="WORK"),