Bénévole : vœux d'artistes (entité Artist) et vœux de postes

Nouvelle entité `Artist` (nom + jour de passage), CRUD
`/editions/{id}/artists` (lecture ouverte à tout compte de l'édition,
écriture COORDINATION), unicité (édition, nom, date).

La fiche bénévole porte deux listes de vœux, sur le modèle de
`skill_codes` (None = inchangé, [] = vider) :
- `artist_ids` : artistes que le bénévole veut voir (`volunteer_artist`) ;
- `wished_position_ids` : postes qu'il voudrait tenir
  (`volunteer_position_wish`), distinct de l'affectation.

Un id étranger à l'édition renvoie 422 (`artist.unknown` /
`position.unknown`). Suppression d'un artiste : cascade sur les vœux.
Migration 0006. Jeu de démonstration et frontend inchangés (le front
suivra).

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017uUsRg7XzopkCPWimwg9ZM

backend/tests/test_api_artists.py

@@ -0,0 +1,114 @@
+import datetime as dt
+import uuid
+
+from sqlmodel import select
+
+from app.models import Artist, Role, VolunteerArtist
+from tests.factories import make_artist, make_volunteer
+
+
+def _url(edition, suffix=""):
+    return f"/editions/{edition.id}/artists{suffix}"
+
+
+def test_create_and_list_ordered_by_date_then_name(client, edition):
+    client.post(
+        _url(edition), json={"name": "Ziak", "performance_date": "2026-07-11"}
+    )
+    client.post(
+        _url(edition), json={"name": "Aloïse Sauvage", "performance_date": "2026-07-11"}
+    )
+    r = client.post(
+        _url(edition), json={"name": "Chilla", "performance_date": "2026-07-10"}
+    )
+    assert r.status_code == 201
+
+    body = client.get(_url(edition)).json()
+    assert [(a["name"], a["performance_date"]) for a in body] == [
+        ("Chilla", "2026-07-10"),
+        ("Aloïse Sauvage", "2026-07-11"),
+        ("Ziak", "2026-07-11"),
+    ]
+
+
+def test_blank_name_is_422(client, edition):
+    r = client.post(
+        _url(edition), json={"name": "   ", "performance_date": "2026-07-10"}
+    )
+    assert r.status_code == 422
+    assert r.json()["detail"]["code"] == "artist.name_required"
+
+
+def test_duplicate_name_and_date_conflicts(client, edition):
+    payload = {"name": "Chilla", "performance_date": "2026-07-10"}
+    assert client.post(_url(edition), json=payload).status_code == 201
+    r = client.post(_url(edition), json=payload)
+    assert r.status_code == 409
+    assert r.json()["detail"]["code"] == "artist.duplicate"
+
+    # Même nom, autre jour : autorisé.
+    r2 = client.post(
+        _url(edition), json={"name": "Chilla", "performance_date": "2026-07-11"}
+    )
+    assert r2.status_code == 201
+
+
+def test_update_artist(client, edition, session):
+    artist = make_artist(session, edition, name="Chila")
+    r = client.patch(
+        _url(edition, f"/{artist.id}"),
+        json={"name": "Chilla", "performance_date": "2026-07-12"},
+    )
+    assert r.status_code == 200
+    assert r.json()["name"] == "Chilla"
+    assert r.json()["performance_date"] == "2026-07-12"
+
+
+def test_delete_artist_removes_volunteer_wishes(client, edition, session):
+    artist = make_artist(session, edition)
+    volunteer = make_volunteer(session, edition, email="fan@e.fr")
+    assert client.patch(
+        f"/editions/{edition.id}/volunteers/{volunteer.id}",
+        json={"artist_ids": [str(artist.id)]},
+    ).json()["artist_ids"] == [str(artist.id)]
+
+    assert client.delete(_url(edition, f"/{artist.id}")).status_code == 204
+    assert session.exec(select(Artist)).all() == []
+    assert session.exec(select(VolunteerArtist)).all() == []
+    fiche = client.get(
+        f"/editions/{edition.id}/volunteers/{volunteer.id}"
+    ).json()
+    assert fiche["artist_ids"] == []
+
+
+def test_unknown_edition_is_404(client):
+    assert client.get(f"/editions/{uuid.uuid4()}/artists").status_code == 404
+
+
+def test_write_is_coordinator_only(edition, make_account, as_account):
+    lead = make_account(Role.LEAD, email="lead@e.fr")
+    api = as_account(lead)
+    resp = api.post(
+        _url(edition), json={"name": "X", "performance_date": "2026-07-10"}
+    )
+    assert resp.status_code == 403
+    # La lecture reste ouverte à tout compte de l'édition.
+    assert api.get(_url(edition)).status_code == 200
+
+
+def test_other_edition_artist_is_404(client, edition, session):
+    from app.models import Edition
+
+    other = Edition(
+        year=2027,
+        start_date=dt.date(2027, 7, 1),
+        end_date=dt.date(2027, 7, 4),
+    )
+    session.add(other)
+    session.commit()
+    session.refresh(other)
+    stranger = make_artist(session, other, name="Ailleurs")
+
+    assert client.patch(
+        _url(edition, f"/{stranger.id}"), json={"name": "Y"}
+    ).status_code == 404