交易服务收敛为仅 rakuten：移除 rakuma 登录态与下单入口

trading 不再管理 ラクマ 的购物车购买、支付与订单监控。删除 auth_site /
auth_session / login_runner / models.AuthSite 中的 rakuma 分支与常量、
account.yaml.example 的 rakuma 段，并清理相关测试。scraping 侧的
ラクマ 抓取 API（/api/rakuma/*）保留不动。

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

tests/test_trading_api.py

@@ -27,7 +27,7 @@ class StubAuthSession:
 
     @property
     def sites(self) -> tuple[str, ...]:
-        return ("rakuten", "rakuma")
+        return ("rakuten",)
 
     def _status(self, site: str) -> AuthStatus:
         return AuthStatus(
@@ -87,7 +87,7 @@ def test_health_needs_no_token(client):
     assert response.status_code == 200
     body = response.json()
     assert body["data"]["status"] == "ok"
-    assert set(body["data"]["auth"]) == {"rakuten", "rakuma"}
+    assert set(body["data"]["auth"]) == {"rakuten"}
 
 
 def test_health_does_not_probe_the_site(client, stub):
@@ -116,12 +116,12 @@ def test_auth_endpoints_reject_wrong_token(client):
 # ---- 登录态查询 ----
 
 
-def test_status_probes_both_sites_by_default(client, stub):
+def test_status_probes_site_by_default(client, stub):
     response = client.post("/api/auth/status", json={}, headers=AUTH)
     assert response.status_code == 200
     body = response.json()
-    assert [item["site"] for item in body["data"]["sites"]] == ["rakuten", "rakuma"]
-    assert stub.checked == ["rakuten", "rakuma"]
+    assert [item["site"] for item in body["data"]["sites"]] == ["rakuten"]
+    assert stub.checked == ["rakuten"]
 
 
 def test_status_can_skip_the_probe(client, stub):
@@ -132,9 +132,9 @@ def test_status_can_skip_the_probe(client, stub):
 
 
 def test_status_accepts_a_single_site(client, stub):
-    response = client.post("/api/auth/status", json={"site": "rakuma"}, headers=AUTH)
+    response = client.post("/api/auth/status", json={"site": "rakuten"}, headers=AUTH)
     assert response.status_code == 200
-    assert stub.checked == ["rakuma"]
+    assert stub.checked == ["rakuten"]
 
 
 def test_status_rejects_unknown_site(client):