fix: use user log stat endpoint for finance upstream costs

backend/app/services/finance_service.py

@@ -166,8 +166,19 @@ def fetch_upstream_cost_sub2api(upstream: Upstream, target_date: date) -> tuple[
 # Upstream cost — New-API / Nox-API
 # ─────────────────────────────────────────────
 
+def _new_api_failure_message(data: Any) -> str | None:
+    if not isinstance(data, dict):
+        return None
+    message = data.get("message") or data.get("detail") or data.get("error")
+    if data.get("success") is False:
+        return str(message or "上游返回 success=false")
+    if message and data.get("error"):
+        return str(message)
+    return None
+
+
 def fetch_upstream_cost_new_api(upstream: Upstream, target_date: date) -> tuple[float, str | None]:
-    """Fetch cost for New-API/Nox-API upstream via /api/log/stat.
+    """Fetch cost for New-API/Nox-API upstream via /api/log/self/stat.
 
     Keeps UpstreamClient open for the full request so that:
     - login_password token refresh is available if the stat call gets 401
@@ -193,9 +204,12 @@ def fetch_upstream_cost_new_api(upstream: Upstream, target_date: date) -> tuple[
             client.ensure_authenticated()
             quota_per_unit = client._new_api_quota_per_unit()
             params = {"type": 2, "start_timestamp": start_ts, "end_timestamp": end_ts}
-            resp = client._send_request("GET", client._url("/api/log/stat"), params=params)
+            resp = client._send_request("GET", client._url("/api/log/self/stat"), params=params)
             resp.raise_for_status()
             data = resp.json()
+            failure_message = _new_api_failure_message(data)
+            if failure_message:
+                return 0.0, failure_message
             payload = data.get("data", data) if isinstance(data, dict) else {}
             if isinstance(payload, dict):
                 quota = payload.get("quota")