feat(profile): add profile settings and LLM user context

backend/tests/test_profile.py

@@ -0,0 +1,35 @@
+def test_get_profile_empty(client):
+    r = client.get("/profile")
+    assert r.status_code == 200
+    assert r.json() is None
+
+
+def test_upsert_profile_create_and_get(client):
+    create = client.patch(
+        "/profile", json={"birth_date": "1990-01-15", "sex_at_birth": "male"}
+    )
+    assert create.status_code == 200
+    body = create.json()
+    assert body["birth_date"] == "1990-01-15"
+    assert body["sex_at_birth"] == "male"
+
+    fetch = client.get("/profile")
+    assert fetch.status_code == 200
+    fetched = fetch.json()
+    assert fetched is not None
+    assert fetched["id"] == body["id"]
+
+
+def test_upsert_profile_updates_existing_row(client):
+    first = client.patch(
+        "/profile", json={"birth_date": "1992-06-10", "sex_at_birth": "female"}
+    )
+    assert first.status_code == 200
+    first_id = first.json()["id"]
+
+    second = client.patch("/profile", json={"sex_at_birth": "intersex"})
+    assert second.status_code == 200
+    second_body = second.json()
+    assert second_body["id"] == first_id
+    assert second_body["birth_date"] == "1992-06-10"
+    assert second_body["sex_at_birth"] == "intersex"