Add fuzzy name search (pg_trgm) and living-person protection

Fuzzy search: pg_trgm extension + trigram GIN indexes on name parts and a GET /trees/{id}/persons?q= search ranked by trigram similarity (finds Mueller for 'muller'), privacy-filtered. Living-person protection: the privacy engine now derives possibly-living status (explicit flag, else no death fact + birth within ~100y or unknown) and returns 'redacted' for non-members of public/unlisted trees; the service minimises those records ('Living person', no vitals). Members are unaffected. 31 tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Signed-off-by: Justin Paul <justin@jpaul.me>

backend/tests/test_privacy_living.py

@@ -0,0 +1,36 @@
+"""Living-person protection: living people are redacted from non-members."""
+
+from tests.conftest import auth, register
+
+
+async def test_living_person_redacted_for_non_members(client):
+    owner = auth(await register(client, "pub-owner@example.com"))
+    tid = (
+        await client.post(
+            "/api/v1/trees", json={"name": "Public", "visibility": "public"}, headers=owner
+        )
+    ).json()["id"]
+    await client.post(
+        f"/api/v1/trees/{tid}/persons",
+        json={"given": "Old", "surname": "Ancestor", "is_living": False},
+        headers=owner,
+    )
+    await client.post(
+        f"/api/v1/trees/{tid}/persons",
+        json={"given": "Young", "surname": "Living", "is_living": True},
+        headers=owner,
+    )
+
+    other = auth(await register(client, "pub-viewer@example.com"))
+    people = (await client.get(f"/api/v1/trees/{tid}/persons", headers=other)).json()
+    names = {p["primary_name"] for p in people}
+    assert "Old Ancestor" in names  # deceased is visible
+    assert "Living person" in names  # living is redacted
+    assert "Young Living" not in names  # the real living name is hidden
+    # The redacted person leaks no gender.
+    living = next(p for p in people if p["primary_name"] == "Living person")
+    assert living["gender"] is None
+
+    # The owner (a member) sees real names.
+    owner_people = (await client.get(f"/api/v1/trees/{tid}/persons", headers=owner)).json()
+    assert "Young Living" in {p["primary_name"] for p in owner_people}