style: apply ruff formatting to all backend files

backend/graph/audit_logs.py

@@ -9,10 +9,7 @@ def fetch_audit_logs(hours: int = 24, since: str | None = None, max_pages: int =
     """Fetch paginated directory audit logs from Microsoft Graph and enrich with resolved names."""
     token = get_access_token()
     start_time = since or (datetime.utcnow() - timedelta(hours=hours)).isoformat() + "Z"
-    next_url = (
-        "https://graph.microsoft.com/v1.0/"
-        f"auditLogs/directoryAudits?$filter=activityDateTime ge {start_time}"
-    )
+    next_url = f"https://graph.microsoft.com/v1.0/auditLogs/directoryAudits?$filter=activityDateTime ge {start_time}"
     headers = {"Authorization": f"Bearer {token}"}
 
     events = []