Allow deleting claims, creating standalone payments, and add a donations tab

Claims could previously only be cancelled (stornieren), which blocks once a
payment is allocated. Add a hard delete that releases any linked
payments/credits back to being unallocated instead of destroying them.

Payments could only be created from within a claim, forcing immediate
allocation. Add a bare payment creation flow in the Zahlungen tab so
incoming transfers can be logged first and allocated later.

Add a per-member Spenden tab (donations, backed by a new donations list on
ContributionData) so amounts paid beyond the membership fee can be tracked
and existing free payments allocated to them.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

tests/test_contributions.py

@@ -9,6 +9,9 @@ from ccma.domain.contributions import (
     claim_settled_total,
     claim_status,
     claim_total,
+    donation_allocated_total,
+    donation_balance,
+    donation_status,
     payment_allocated_total,
 )
 from ccma.domain.models import ContributionData
@@ -311,6 +314,133 @@ def test_claim_with_payment_cannot_be_cancelled(tmp_path) -> None:
         repository.cancel_claim(member.member_id, "claim-1")
 
 
+def test_claim_can_be_deleted_and_releases_allocated_payment(tmp_path) -> None:
+    repository, member = _repository_with_claim(tmp_path)
+    payment = repository.record_payment(
+        member.member_id,
+        "claim-1",
+        payment_date="2026-06-21",
+        amount="60.00",
+        allocation_amount="60.00",
+    )
+
+    repository.delete_claim(member.member_id, "claim-1")
+
+    data = repository.get_contributions(member.member_id)
+    assert data.claims == []
+    assert data.allocations == []
+    assert data.payments[0]["payment_id"] == payment["payment_id"]
+    assert payment_allocated_total(data, payment["payment_id"]) == Decimal("0.00")
+    assert repository.get_events(member.member_id)[-1].event_type == "claim_deleted"
+
+    with pytest.raises(RepositoryError, match="nicht gefunden"):
+        repository.get_claim(member.member_id, "claim-1")
+
+
+def test_claim_with_payment_can_be_deleted_even_though_it_cannot_be_cancelled(tmp_path) -> None:
+    repository, member = _repository_with_claim(tmp_path)
+    repository.record_payment(
+        member.member_id,
+        "claim-1",
+        payment_date="2026-06-21",
+        amount="10.00",
+        allocation_amount="10.00",
+    )
+
+    with pytest.raises(RepositoryError, match="Zahlungszuordnungen"):
+        repository.cancel_claim(member.member_id, "claim-1")
+
+    repository.delete_claim(member.member_id, "claim-1")
+    assert repository.get_contributions(member.member_id).claims == []
+
+
+def test_bare_payment_can_be_created_without_allocation(tmp_path) -> None:
+    repository = MemberRepository(tmp_path)
+    repository.initialize()
+    member = repository.create_member(first_name="Payment", last_name="Test")
+
+    payment = repository.create_payment(
+        member.member_id,
+        payment_date="2026-06-21",
+        amount="42.00",
+        reference="Überweisung ohne Zuordnung",
+    )
+
+    data = repository.get_contributions(member.member_id)
+    assert data.payments == [payment]
+    assert data.allocations == []
+    assert payment_allocated_total(data, payment["payment_id"]) == Decimal("0.00")
+    assert repository.get_events(member.member_id)[-1].event_type == "payment_recorded"
+
+
+def test_donation_can_be_recorded_paid_and_deleted_releases_payment(tmp_path) -> None:
+    repository = MemberRepository(tmp_path)
+    repository.initialize()
+    member = repository.create_member(first_name="Donation", last_name="Test")
+
+    donation = repository.record_donation(
+        member.member_id,
+        donation_date="2026-06-21",
+        amount="30.00",
+        reference="Sommerfest",
+        purpose="Freiwillige Zusatzspende",
+    )
+    data = repository.get_contributions(member.member_id)
+    assert donation_status(data, donation) == "open"
+    assert donation_balance(data, donation) == Decimal("30.00")
+
+    payment = repository.record_donation_payment(
+        member.member_id,
+        donation["donation_id"],
+        payment_date="2026-06-22",
+        amount="30.00",
+        allocation_amount="30.00",
+    )
+    data = repository.get_contributions(member.member_id)
+    assert donation_allocated_total(data, donation["donation_id"]) == Decimal("30.00")
+    assert donation_status(data, donation) == "allocated"
+
+    repository.delete_donation(member.member_id, donation["donation_id"])
+    data = repository.get_contributions(member.member_id)
+    assert data.donations == []
+    assert data.allocations == []
+    assert data.payments[0]["payment_id"] == payment["payment_id"]
+    assert payment_allocated_total(data, payment["payment_id"]) == Decimal("0.00")
+    assert repository.get_events(member.member_id)[-1].event_type == "donation_deleted"
+
+
+def test_existing_free_payment_can_be_allocated_to_a_donation(tmp_path) -> None:
+    repository = MemberRepository(tmp_path)
+    repository.initialize()
+    member = repository.create_member(first_name="Donation", last_name="Allocate")
+
+    payment = repository.create_payment(
+        member.member_id,
+        payment_date="2026-06-21",
+        amount="100.00",
+        reference="Mitgliedsbeitrag plus Spende",
+    )
+    donation = repository.record_donation(
+        member.member_id,
+        donation_date="2026-06-21",
+        amount="20.00",
+        reference="Aufrundung",
+    )
+
+    repository.allocate_payment_to_donation(
+        member.member_id, donation["donation_id"], payment_id=payment["payment_id"], amount="20.00"
+    )
+
+    data = repository.get_contributions(member.member_id)
+    assert donation_balance(data, donation) == Decimal("0.00")
+    assert payment_allocated_total(data, payment["payment_id"]) == Decimal("20.00")
+
+    with pytest.raises(RepositoryError, match="nur noch 0.00 EUR"):
+        repository.allocate_payment_to_donation(
+            member.member_id, donation["donation_id"], payment_id=payment["payment_id"], amount="1.00"
+        )
+
+
 def test_gnucash_id_is_unique_across_member_store(tmp_path) -> None:
     repository, first_member = _repository_with_claim(tmp_path / "store")
     repository.record_payment(