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/sync/playlists.py

@@ -5,6 +5,7 @@ edits out to YouTube (`plan_push` / `push_playlist`), behind the optional write
 YouTube's special Watch Later / History playlists are not exposed by the Data API and are
 never synced. Videos in a playlist that aren't in our shared catalog yet are fetched and
 ingested (with a stub channel) so the mirror is faithful."""
+
 import hashlib
 import logging
 from collections.abc import Callable
@@ -59,9 +60,7 @@ def _ensure_videos(db: Session, yt: YouTubeClient, video_ids: list[str]) -> None
     the API won't return are simply left out."""
     if not video_ids:
         return
-    have = set(
-        db.execute(select(Video.id).where(Video.id.in_(video_ids))).scalars().all()
-    )
+    have = set(db.execute(select(Video.id).where(Video.id.in_(video_ids))).scalars().all())
     missing = [v for v in dict.fromkeys(video_ids) if v not in have]
     if not missing:
         return
@@ -109,9 +108,7 @@ def _replace_items_from_youtube(
     ordered ids."""
     _ensure_videos(db, yt, ids)
     present = (
-        set(db.execute(select(Video.id).where(Video.id.in_(ids))).scalars().all())
-        if ids
-        else set()
+        set(db.execute(select(Video.id).where(Video.id.in_(ids))).scalars().all()) if ids else set()
     )
     ordered: list[str] = []
     seen: set[str] = set()
@@ -139,9 +136,7 @@ def sync_user_playlists(db: Session, user: User) -> dict:
         existing = {
             pl.yt_playlist_id: pl
             for pl in db.execute(
-                select(Playlist).where(
-                    Playlist.user_id == user.id, Playlist.source == "youtube"
-                )
+                select(Playlist).where(Playlist.user_id == user.id, Playlist.source == "youtube")
             ).scalars()
         }
         # YouTube playlists that we already own as local (exported) playlists must not be