Raise UnauthorizedError when RdSAP Summary fetch returns 401 🟩

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

backend/pashub_fetcher/pashub_client.py

@@ -137,6 +137,8 @@ class PashubClient:
         url = f"{self.base}/jobs/{job_id}/rdSapSummary"
 
         r = self.session.get(url)
+        if r.status_code == 401:
+            raise UnauthorizedError("Token expired or invalid")
 
         data: Dict[str, Any] = r.json()
         return RdSapSummary(