style: apply ruff format across backend + scripts (line-length 100)

Mechanical, whole-tree `ruff format` pass — no behaviour change. Recorded in
.git-blame-ignore-revs (next commit) so git blame skips it.

backend/app/routes/setup.py

@@ -5,6 +5,7 @@ mutating step goes through `require_setup`: it rejects once the instance is conf
 the one-time setup token (printed to the container logs at first boot, carried by the wizard as the
 X-Setup-Token header).
 """
+
 from typing import Any
 
 from fastapi import APIRouter, Depends, Header, HTTPException