fix: 修正空白加班餐扣归属计算

tests/test_report_allocations.py

@@ -221,6 +221,23 @@ def test_night_allocation_uses_meal_deducted_minutes_with_previous_date_rules():
     ]
 
 
+def test_blank_overtime_meal_deduction_is_clipped_like_metrics():
+    start_at = datetime(2026, 7, 25, 6, 0)
+    end_at = datetime(2026, 7, 25, 19, 0)
+    item = _item(id=1, good_qty=680)
+    report = _report(start_at, end_at, item)
+
+    metrics = calculate_report_metrics(start_at, end_at, [item])
+    rows = build_report_allocation_drafts(report)
+
+    assert metrics["effective_minutes"] == 680
+    assert metrics["shift_day_minutes"] == 500
+    assert metrics["shift_overtime_minutes"] == 180
+    assert [(row.effective_minutes, row.day_minutes, row.overtime_minutes, row.night_minutes) for row in rows] == [
+        (680, 500, 180, 0),
+    ]
+
+
 def test_zero_effective_minutes_falls_back_to_original_report_date():
     item = _item(good_qty=5, defect_qty=1, scrap_qty=0.5, changeover_count=2, process_unit_price_yuan=3)
     report = _report(