feat: add staged reminder workflow

tests/test_contributions.py

@@ -105,19 +105,31 @@ def test_payment_can_be_split_across_multiple_claims(tmp_path) -> None:
 def test_reminder_fee_increases_claim_and_is_audited(tmp_path) -> None:
     repository, member = _repository_with_claim(tmp_path)
 
-    reminder = repository.add_reminder(
+    reminder = repository.create_reminder_draft(
         member.member_id,
         "claim-1",
         level=1,
+        name="Zahlungserinnerung",
+        payment_deadline_days=14,
         detail="Per E-Mail versandt",
         fee="5.00",
     )
     data, claim = repository.get_claim(member.member_id, "claim-1")
 
+    assert claim_total(claim) == Decimal("100.00")
+    assert reminder["status"] == "draft"
+    assert reminder["fee_item_id"] is None
+
+    repository.mark_reminder_sent(member.member_id, "claim-1", reminder["reminder_id"])
+    data, claim = repository.get_claim(member.member_id, "claim-1")
+    sent = data.reminders[0]
+
     assert claim_total(claim) == Decimal("105.00")
-    assert reminder["fee_item_id"]
+    assert sent["status"] == "sent"
+    assert sent["payment_deadline"]
+    assert sent["fee_item_id"]
     assert data.reminders[0]["detail"] == "Per E-Mail versandt"
-    assert repository.get_events(member.member_id)[-1].event_type == "reminder_created"
+    assert repository.get_events(member.member_id)[-1].event_type == "reminder_sent"
 
 
 def test_claim_with_payment_cannot_be_cancelled(tmp_path) -> None: