feat: let a user_id ticket carry an email, accept frontend_url

`CreateTicket` no longer rejects `user_id` together with `name`/`email`
(the exclusion was a fork-only dispatch convenience from dfabcb8; nothing
needed it). `crud.create_ticket` stops blanking name/email when a user_id
is present, so logged-in webapp buyers can have their ticket emailed —
until now `_send_ticket_notification` short-circuited on the empty
address for every app purchase.

New optional `frontend_url` (absolute http(s) root, no query/fragment/..,
trailing slash stripped) lets a buyer-side client name the app the buyer
should be returned to and linked into from the ticket email; the origin
allow-list lives in views_api.

Also folds in the pending black reflow of migrations_fork.py.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EYwoAkZZmXMMmaBp4WGUBo

tests/test_crud_ticket_email.py

@@ -0,0 +1,48 @@
+from unittest.mock import AsyncMock
+
+import pytest
+
+from .. import crud
+
+
+@pytest.mark.asyncio
+async def test_create_ticket_keeps_email_alongside_user_id(monkeypatch):
+    inserted = {}
+
+    async def fake_insert(table, model):
+        inserted["table"] = table
+        inserted["model"] = model
+
+    monkeypatch.setattr(crud.db, "insert", AsyncMock(side_effect=fake_insert))
+
+    ticket = await crud.create_ticket(
+        payment_hash="hash",
+        wallet="w",
+        event="e",
+        name="Ada",
+        email="ada@example.com",
+        user_id="u1",
+        ticket_id="t1",
+    )
+
+    assert inserted["table"] == "events.ticket"
+    assert inserted["model"].user_id == "u1"
+    assert inserted["model"].email == "ada@example.com"
+    assert inserted["model"].name == "Ada"
+    assert ticket.email == "ada@example.com"
+
+
+@pytest.mark.asyncio
+async def test_create_ticket_stores_empty_string_sentinels(monkeypatch):
+    inserted = {}
+
+    async def fake_insert(table, model):
+        inserted["model"] = model
+
+    monkeypatch.setattr(crud.db, "insert", AsyncMock(side_effect=fake_insert))
+
+    await crud.create_ticket(
+        payment_hash="hash", wallet="w", event="e", user_id="u1", ticket_id="t2"
+    )
+    assert inserted["model"].email == ""
+    assert inserted["model"].name == ""

tests/test_ticket_models.py

@@ -0,0 +1,110 @@
+import pytest
+from pydantic import ValidationError
+
+from ..models import (
+    CreateEvent,
+    CreateTicket,
+    EventExtra,
+    effective_payment_methods,
+)
+
+
+def _ticket(**kwargs) -> CreateTicket:
+    return CreateTicket(**kwargs)
+
+
+def test_user_id_only_is_a_valid_identity():
+    assert _ticket(user_id="u1").user_id == "u1"
+
+
+def test_name_and_email_is_a_valid_guest_identity():
+    ticket = _ticket(name="Guest", email="guest@example.com")
+    assert ticket.user_id is None
+    assert ticket.email == "guest@example.com"
+
+
+def test_user_id_may_carry_an_email_for_delivery():
+    ticket = _ticket(user_id="u1", email="me@example.com")
+    assert ticket.user_id == "u1"
+    assert ticket.email == "me@example.com"
+
+
+@pytest.mark.parametrize(
+    "kwargs",
+    [
+        {},
+        {"name": "Guest"},
+        {"email": "guest@example.com"},
+    ],
+)
+def test_missing_identity_is_rejected(kwargs):
+    with pytest.raises(ValidationError):
+        _ticket(**kwargs)
+
+
+@pytest.mark.parametrize(
+    "url,expected",
+    [
+        ("https://app.example/events", "https://app.example/events"),
+        ("https://app.example/events/", "https://app.example/events"),
+        ("http://localhost:5173/", "http://localhost:5173"),
+        ("  ", None),
+    ],
+)
+def test_frontend_url_is_normalised(url, expected):
+    assert _ticket(user_id="u1", frontend_url=url).frontend_url == expected
+
+
+@pytest.mark.parametrize(
+    "url",
+    [
+        "/events",  # relative
+        "ftp://app.example/events",
+        "https://app.example/events?x=1",
+        "https://app.example/events#top",
+        "https://app.example/../events",
+        "https://" + "a" * 520,
+    ],
+)
+def test_frontend_url_rejects_unsafe_values(url):
+    with pytest.raises(ValidationError):
+        _ticket(user_id="u1", frontend_url=url)
+
+
+def _event(**overrides) -> CreateEvent:
+    data = {
+        "wallet": "w",
+        "name": "Test",
+        "info": "",
+        "closing_date": "2030-01-01",
+        "event_start_date": "2030-01-01",
+        "event_end_date": "2030-01-02",
+        "amount_tickets": 10,
+        "price_per_ticket": 5,
+    }
+    data.update(overrides)
+    return CreateEvent(**data)
+
+
+def test_effective_payment_methods_legacy_rule():
+    assert effective_payment_methods(_event()) == ["lightning"]
+    assert effective_payment_methods(_event(allow_fiat=True)) == ["lightning", "fiat"]
+
+
+def test_effective_payment_methods_explicit_list_wins():
+    event = _event(allow_fiat=True, extra=EventExtra(payment_methods=["fiat"]))
+    assert effective_payment_methods(event) == ["fiat"]
+
+
+def test_payment_methods_are_normalised_and_deduplicated():
+    extra = EventExtra(payment_methods=["Fiat", " lightning ", "fiat"])
+    assert extra.payment_methods == ["fiat", "lightning"]
+    assert EventExtra(payment_methods="lightning,fiat").payment_methods == [
+        "lightning",
+        "fiat",
+    ]
+
+
+def test_unknown_payment_method_is_rejected():
+    with pytest.raises(ValidationError):
+        EventExtra(payment_methods=["cash"])