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_search.py

@@ -0,0 +1,24 @@
+"""Fuzzy name search (pg_trgm)."""
+
+from tests.conftest import auth, register
+
+
+async def test_fuzzy_name_search(client):
+    h = auth(await register(client, "search@example.com"))
+    tid = (await client.post("/api/v1/trees", json={"name": "S"}, headers=h)).json()["id"]
+    for given, surname in [("Hans", "Mueller"), ("John", "Smith"), ("Anna", "Vogel")]:
+        await client.post(
+            f"/api/v1/trees/{tid}/persons",
+            json={"given": given, "surname": surname},
+            headers=h,
+        )
+
+    # Trigram fuzziness: "muller" should find "Mueller" (not a substring match).
+    r = await client.get(f"/api/v1/trees/{tid}/persons", params={"q": "muller"}, headers=h)
+    assert r.status_code == 200
+    names = [p["primary_name"] or "" for p in r.json()]
+    assert any("Mueller" in n for n in names)
+
+    # Substring search still works.
+    r2 = await client.get(f"/api/v1/trees/{tid}/persons", params={"q": "smi"}, headers=h)
+    assert any("Smith" in (p["primary_name"] or "") for p in r2.json())