feat: extend inventory and administration workflows

tests/test_dates.py

@@ -58,6 +58,15 @@ def test_member_dates_must_be_chronological() -> None:
             today=date(2026, 6, 21),
         )
 
+    with pytest.raises(DateValidationError, match="Austrittsdatum"):
+        validate_member_dates(
+            birth_date="2000-01-01",
+            accepted_at="2020-01-01",
+            membership_started_at="2020-02-01",
+            membership_ended_at="2020-01-31",
+            today=date(2026, 6, 21),
+        )
+
 
 def test_age_calculation_and_label() -> None:
     today = date(2026, 6, 21)