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/main.py

@@ -12,9 +12,7 @@ from fastapi import FastAPI, HTTPException
 _siftlode_logger = logging.getLogger("siftlode")
 if not _siftlode_logger.handlers:
     _handler = logging.StreamHandler(sys.stdout)
-    _handler.setFormatter(
-        logging.Formatter("%(asctime)s %(levelname)-5s [%(name)s] %(message)s")
-    )
+    _handler.setFormatter(logging.Formatter("%(asctime)s %(levelname)-5s [%(name)s] %(message)s"))
     _siftlode_logger.addHandler(_handler)
     _siftlode_logger.setLevel(logging.INFO)
     _siftlode_logger.propagate = False
@@ -140,9 +138,7 @@ async def setup_gate(request, call_next):
             with SessionLocal() as db:
                 configured = state.is_configured_cached(db)
             if not configured:
-                return JSONResponse(
-                    {"detail": "This instance isn't set up yet."}, status_code=503
-                )
+                return JSONResponse({"detail": "This instance isn't set up yet."}, status_code=503)
     return await call_next(request)