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/plex/lookups.py

@@ -1,4 +1,5 @@
 """Small shared Plex row lookups, so the get-by-rating_key pattern lives in one place."""
+
 from typing import TypeVar
 
 from sqlalchemy import select
@@ -11,6 +12,4 @@ def by_rating_key(db: Session, model: type[_M], rating_key: str) -> _M | None:
     """The mirrored row for a Plex rating_key, or None. `model` is any of the rating_key-keyed Plex
     tables (PlexItem / PlexShow / PlexSeason / PlexCollection); the return type is that model, so call
     sites keep their `Model | None` static type."""
-    return db.execute(
-        select(model).where(model.rating_key == str(rating_key))
-    ).scalars().first()
+    return db.execute(select(model).where(model.rating_key == str(rating_key))).scalars().first()