Alternate names (maiden/married), self-person link, deletion integrity

Names (the genealogy standard: maiden name primary, married/alias as typed
alternates):
- Name model already supported multiple typed names; expose full CRUD —
  NameCreate/Read/Update schemas, name_service (one-primary invariant,
  promote-on-delete), nested /persons/{id}/names routes.
- Person page gains a Names card: add/edit/delete + "make primary", with a
  curated name_type dropdown (birth/maiden, married, alias, nickname, …).

Self-person ("who am I"):
- users.self_person_id FK (use_alter for the users<->persons<->trees cycle)
  + migration; PATCH /users/me/self-person; "This is me" / "This is you"
  on the person page. Soft-deleting the linked person clears it.

Deletion integrity (fixes the broken tree view):
- delete_person now soft-deletes the relationships touching the person, so no
  dangling edges remain; family-chart also filters links to missing people.
- Optional cascade=true recursively deletes descendants (GEDCOM cleanup);
  the person page asks "only this person" vs "with all descendants".
- DELETE returns {deleted: n}.

Family view surfaces "Not connected to anyone" so dangling people aren't lost.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/tests/test_delete_and_self.py

@@ -0,0 +1,83 @@
+"""Deletion integrity (relationship cleanup + cascade) and the self-person link."""
+
+from tests.conftest import auth, register
+
+
+async def _setup(client, email):
+    h = auth(await register(client, email))
+    tid = (await client.post("/api/v1/trees", json={"name": "T"}, headers=h)).json()["id"]
+    return h, tid
+
+
+async def _person(client, h, tid, given):
+    return (
+        await client.post(f"/api/v1/trees/{tid}/persons", json={"given": given}, headers=h)
+    ).json()["id"]
+
+
+async def _link_parent(client, h, tid, parent, child):
+    await client.post(
+        f"/api/v1/trees/{tid}/relationships",
+        json={"type": "parent_child", "person_from_id": parent, "person_to_id": child},
+        headers=h,
+    )
+
+
+async def test_delete_removes_relationships(client):
+    h, tid = await _setup(client, "d-rels@example.com")
+    gp = await _person(client, h, tid, "Grandpa")
+    dad = await _person(client, h, tid, "Dad")
+    await _link_parent(client, h, tid, gp, dad)
+
+    r = await client.delete(f"/api/v1/trees/{tid}/persons/{gp}", headers=h)
+    assert r.status_code == 200 and r.json()["deleted"] == 1
+
+    # The dangling edge is gone, so the tree view can't break on it.
+    rels = (
+        await client.get(f"/api/v1/trees/{tid}/relationships", headers=h)
+    ).json()
+    assert rels == []
+    # Dad survives.
+    ppl = {p["id"] for p in (await client.get(f"/api/v1/trees/{tid}/persons", headers=h)).json()}
+    assert dad in ppl and gp not in ppl
+
+
+async def test_cascade_deletes_descendants(client):
+    h, tid = await _setup(client, "d-cascade@example.com")
+    gp = await _person(client, h, tid, "Grandpa")
+    dad = await _person(client, h, tid, "Dad")
+    kid = await _person(client, h, tid, "Kid")
+    await _link_parent(client, h, tid, gp, dad)
+    await _link_parent(client, h, tid, dad, kid)
+
+    r = await client.delete(f"/api/v1/trees/{tid}/persons/{gp}?cascade=true", headers=h)
+    assert r.status_code == 200 and r.json()["deleted"] == 3
+    ppl = (await client.get(f"/api/v1/trees/{tid}/persons", headers=h)).json()
+    assert ppl == []
+
+
+async def test_self_person_link(client):
+    h, tid = await _setup(client, "self@example.com")
+    me = await _person(client, h, tid, "Me")
+
+    r = await client.patch(
+        "/api/v1/users/me/self-person", json={"self_person_id": me}, headers=h
+    )
+    assert r.status_code == 200 and r.json()["self_person_id"] == me
+
+    # Reflected on /me.
+    assert (await client.get("/api/v1/users/me", headers=h)).json()["self_person_id"] == me
+
+    # Deleting that person clears the link (SET NULL).
+    await client.delete(f"/api/v1/trees/{tid}/persons/{me}", headers=h)
+    assert (await client.get("/api/v1/users/me", headers=h)).json()["self_person_id"] is None
+
+
+async def test_self_person_clear(client):
+    h, tid = await _setup(client, "self-clear@example.com")
+    me = await _person(client, h, tid, "Me")
+    await client.patch("/api/v1/users/me/self-person", json={"self_person_id": me}, headers=h)
+    r = await client.patch(
+        "/api/v1/users/me/self-person", json={"self_person_id": None}, headers=h
+    )
+    assert r.status_code == 200 and r.json()["self_person_id"] is None